Improve DTrace probe generation /w non-default compiler

With DTrace support enabled during ./configure, our custom Autoconf
macro PHP_INIT_DTRACE creates make rules to generate header and object
files using dtrace utility. SystemTap† implementation of dtrace relies
on other utilities to provide header preprocessing and final object file
compilation. These utilities are configured by common environment
variables with common defaults:‡

* preprocessor from CPP defaults to “cpp”
* compiler from CC defaults to “gcc”
* compiler arguments can be expanded with CFLAGS

This has been in SystemTap since version 1.5 released on 2011-05-23. We
have been setting CFLAGS for dtrace since 717b367 released in versions
5.4.20 and 5.5.4 on 2013-09-18. This change fixed build against
SystemTap. It fixes majority of cases since practically all free Linux
distributions use SystemTap for DTrace-like dynamic tracing and
practically all of them use GCC or compatible compiler suite. However,
this becomes an issue when cross-compiling using GCC because utility
names contain target triplets. Autoconf already handles
cross-compilation well —setting correct CC and CPP make macros
(variables).

Therefore, we simply set CC and CPP environment variables using
respective macros when executing dtrace. Although SystemTap dtrace does
not always use CC nor CPP, we set it every time. SystemTap documentation
does not talk about this at all¶, so it is safer to always set it. We
also follow how we set CFLAGS every time in the past.

Original (or ported) DTrace mainly used on Oracle Linux, Solaris and
macOS ignores these and does not support cross compilation.§

† Well-known dynamic tracing infrastructure for Linux compatible with
statically-defined tracing from DTrace.
‡ https://sourceware.org/git/?p=systemtap.git;a=blob;f=dtrace.in;h=73a6f22e2de072773c692e3fea05c4b8cf814e43;hb=ebb424eee5599fcc131901c0d82d0bfc0d2f57ab
¶ https://sourceware.org/systemtap/man/dtrace.1.html
§ https://docs.oracle.com/cd/E88353_01/html/E72487/dtrace-8.html

Closes GH-11643

Author: f4z4on

build/php.m4

@@ -2389,7 +2389,7 @@ dnl overwritten (Bug 61268).
 $abs_srcdir/$ac_provsrc:;
 
 $ac_bdir[$]ac_hdrobj: $abs_srcdir/$ac_provsrc
-	CFLAGS="\$(CFLAGS_CLEAN)" dtrace -h -C -s $ac_srcdir[$]ac_provsrc -o \$[]@.bak && \$(SED) -e 's,PHP_,DTRACE_,g' \$[]@.bak > \$[]@
+	CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -h -C -s $ac_srcdir[$]ac_provsrc -o \$[]@.bak && \$(SED) -e 's,PHP_,DTRACE_,g' \$[]@.bak > \$[]@
 
 \$(PHP_DTRACE_OBJS): $ac_bdir[$]ac_hdrobj
 
@@ -2409,12 +2409,12 @@ EOF
 $ac_bdir[$]ac_provsrc.lo: \$(PHP_DTRACE_OBJS)
 	echo "[#] Generated by Makefile for libtool" > \$[]@
 	@test -d "$dtrace_lib_dir" || mkdir $dtrace_lib_dir
-	if CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $dtrace_d_obj -s $abs_srcdir/$ac_provsrc $dtrace_lib_objs 2> /dev/null && test -f "$dtrace_d_obj"; then [\\]
+	if CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $dtrace_d_obj -s $abs_srcdir/$ac_provsrc $dtrace_lib_objs 2> /dev/null && test -f "$dtrace_d_obj"; then [\\]
 	  echo "pic_object=['].libs/$dtrace_prov_name[']" >> \$[]@ [;\\]
 	else [\\]
 	  echo "pic_object='none'" >> \$[]@ [;\\]
 	fi
-	if CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $ac_bdir[$]ac_provsrc.o -s $abs_srcdir/$ac_provsrc $dtrace_nolib_objs 2> /dev/null && test -f "$ac_bdir[$]ac_provsrc.o"; then [\\]
+	if CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $ac_bdir[$]ac_provsrc.o -s $abs_srcdir/$ac_provsrc $dtrace_nolib_objs 2> /dev/null && test -f "$ac_bdir[$]ac_provsrc.o"; then [\\]
 	  echo "non_pic_object=[']$dtrace_prov_name[']" >> \$[]@ [;\\]
 	else [\\]
 	  echo "non_pic_object='none'" >> \$[]@ [;\\]
@@ -2426,7 +2426,7 @@ EOF
   *)
 cat>>Makefile.objects<<EOF
 $ac_bdir[$]ac_provsrc.o: \$(PHP_DTRACE_OBJS)
-	CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o \$[]@ -s $abs_srcdir/$ac_provsrc $dtrace_objs
+	CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o \$[]@ -s $abs_srcdir/$ac_provsrc $dtrace_objs
 
 EOF
     ;;

ext/oci8/config.m4

@@ -124,7 +124,7 @@ dnl overwritten (Bug 61268).
 PHP_EXT_SRCDIR([oci8])/$ac_provsrc:;
 
 $ac_bdir[$]ac_hdrobj: $ac_srcdir[$]ac_provsrc
-	CFLAGS="\$(CFLAGS_CLEAN)" dtrace -h -C -s $ac_srcdir[$]ac_provsrc -o \$[]@.bak && \$(SED) -e 's,PHPOCI_,DTRACE_,g' \$[]@.bak > \$[]@
+	CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -h -C -s $ac_srcdir[$]ac_provsrc -o \$[]@.bak && \$(SED) -e 's,PHPOCI_,DTRACE_,g' \$[]@.bak > \$[]@
 
 \$(OCI8_DTRACE_OBJS): $ac_bdir[$]ac_hdrobj
 
@@ -145,12 +145,12 @@ EOF
 $ac_bdir[$]ac_provsrc.lo: \$(OCI8_DTRACE_OBJS)
 	echo "[#] Generated by Makefile for libtool" > \$[]@
 	@test -d "$dtrace_lib_dir" || mkdir $dtrace_lib_dir
-	if CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $dtrace_d_obj -s $ac_srcdir[$]ac_provsrc $dtrace_oci8_lib_objs 2> /dev/null && test -f "$dtrace_d_obj"; then [\\]
+	if CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $dtrace_d_obj -s $ac_srcdir[$]ac_provsrc $dtrace_oci8_lib_objs 2> /dev/null && test -f "$dtrace_d_obj"; then [\\]
 	  echo "pic_object=['].libs/$dtrace_prov_name[']" >> \$[]@ [;\\]
 	else [\\]
 	  echo "pic_object='none'" >> \$[]@ [;\\]
 	fi
-	if CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $ac_bdir[$]ac_provsrc.o -s $ac_srcdir[$]ac_provsrc $dtrace_nolib_objs 2> /dev/null && test -f "$ac_bdir[$]ac_provsrc.o"; then [\\]
+	if CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o $ac_bdir[$]ac_provsrc.o -s $ac_srcdir[$]ac_provsrc $dtrace_nolib_objs 2> /dev/null && test -f "$ac_bdir[$]ac_provsrc.o"; then [\\]
 	  echo "non_pic_object=[']$dtrace_prov_name[']" >> \$[]@ [;\\]
 	else [\\]
 	  echo "non_pic_object='none'" >> \$[]@ [;\\]
@@ -162,7 +162,7 @@ EOF
     AC_MSG_WARN([OCI8 extension: OCI8 DTrace support is not confirmed on this platform])
 cat>>Makefile.objects<<EOF
 $ac_bdir[$]ac_provsrc.o: \$(OCI8_DTRACE_OBJS)
-	CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o \$[]@ -s $ac_srcdir[$]ac_provsrc $dtrace_oci8_objs
+	CPP="\$(CPP)" CC="\$(CC)" CFLAGS="\$(CFLAGS_CLEAN)" dtrace -G -o \$[]@ -s $ac_srcdir[$]ac_provsrc $dtrace_oci8_objs
 
 EOF
     ;;