GCC's x86 and s390 ports support -mrecord-mcount. Other ports reject the
option.
aarch64-linux-gnu-gcc: error: unrecognized command line option ‘-mrecord-mcount’
Allowing this option can cause failures when building Linux kernel for
aarch64, powerpc64, etc, which will think the feature is available if
the clang command returns 0.
Recognize -mrecord-mcount from the command line and add a function attribute
"mrecord-mcount" when passed.
Only valid on SystemZ (when used with -mfentry).
Review: Ulrich Weigand
https://reviews.llvm.org/D71627