ppc64le and s390x 1.13.0 binaries segfault when trying to build 1.14.0

[infinity0]

s390x: https://buildd.debian.org/status/fetch.php?pkg=rustc&arch=s390x&ver=1.14.0%2Bdfsg1-1&stamp=1482615802

CFG_LLVM_LINKAGE_FILE=/«BUILDDIR»/rustc-1.14.0+dfsg1/s390x-unknown-linux-gnu/rt/llvmdeps.rs LD_LIBRARY_PATH=/«BUILDDIR»/rustc-1.14.0+dfsg1/s390x-unknown-linux-gnu/stage2/lib:/usr/lib/llvm-3.9/lib:$LD_LIBRARY_PATH   s390x-unknown-linux-gnu/stage2/bin/rustc --cfg stage2 -C link-args=-Wl,-z,relro -O --cfg rtopt -Cdebuginfo=1 -C rpath  --target=s390x-unknown-linux-gnu  -C prefer-dynamic -L "s390x-unknown-linux-gnu/rt" -L native="/usr/lib/llvm-3.9/lib"     --out-dir s390x-unknown-linux-gnu/stage2/lib/rustlib/s390x-unknown-linux-gnu/lib -C extra-filename=-f5a209a9 -C metadata=f5a209a9 src/libcore/lib.rs
Segmentation fault

ppc64el: https://buildd.debian.org/status/fetch.php?pkg=rustc&arch=ppc64el&ver=1.14.0%2Bdfsg1-1&stamp=1482614656

checking for secure_getenv... Segmentation fault

No time atm to investigate further, but will follow this up with more info in the new year.

[infinity0]

Probably same as or related to #37320, see also #38612.