liblzma: Fix false Valgrind error report with GCC.

liblzma: Fix false Valgrind error report with GCC.

With GCC and a certain combination of flags, Valgrind will falsely
trigger an invalid write. This appears to be due to the omission of
instructions to properly save, set up, and restore the frame pointer.

The IFUNC resolver is a leaf function since it only calls a function
that is inlined. So sometimes GCC omits the frame pointer instructions
in the resolver unless this optimization is explictly disabled.

This fixes https://bugzilla.redhat.com/show_bug.cgi?id=2267598.