Regarding recently fixed 8284437: Building from different users/workspace is not always deterministic

[Maxim Kartashev]

I was wondering if perhaps someone can comment on why were the changes (see
https://github.com/openjdk/jdk/pull/8124/files) made in
make/autoconf/flags-cflags.m4 for 8284437
<https://bugs.openjdk.java.net/browse/JDK-8284437> confined solely to the
gcc branch
if test "x$TOOLCHAIN_TYPE" = xgcc; then ...
and not also propagated to the clang branch down below
elif test "x$TOOLCHAIN_TYPE" = xclang; then ...
? It seems like the same would be required to make builds by clang
reproducible and clang does support the same option, spelling and all.

(sorry I didn't make the comment earlier in the PR
<https://github.com/openjdk/jdk/pull/8124> itself).