bpo-35257: fix broken BLDSHARED - needs LDFLAGS too (GH-11297)

`BLDSHARED` needs to have both `LDFLAGS` and `LDFLAGS_NODIST`, not just `LDFLAGS_NODIST`; `PY_CORE_LDFLAGS` provides both.  For example, as it stands now with just `LDFLAGS_NODIST`, macOS universal builds are broken as the necessary `-arch` flags are no longer passed to the standard library extension module link step from `setup.py` resulting in extension modules being single architecture only.

https://bugs.python.org/issue35257
(cherry picked from commit 44a3ee0)

Co-authored-by: Ned Deily <[email protected]>

Author: miss-islington

Makefile.pre.in

@@ -155,7 +155,7 @@ CONFINCLUDEPY=	$(CONFINCLUDEDIR)/python$(LDVERSION)
 SHLIB_SUFFIX=	@SHLIB_SUFFIX@
 EXT_SUFFIX=	@EXT_SUFFIX@
 LDSHARED=	@LDSHARED@ $(PY_LDFLAGS)
-BLDSHARED=	@BLDSHARED@ $(PY_LDFLAGS_NODIST)
+BLDSHARED=	@BLDSHARED@ $(PY_CORE_LDFLAGS)
 LDCXXSHARED=	@LDCXXSHARED@
 DESTSHARED=	$(BINLIBDEST)/lib-dynload