Top level:
Merge from GCC:
PR bootstrap/82856
* multilib.am: New file. From automake.
config:
Merge from GCC:
PR bootstrap/82856
* math.m4, tls.m4: Use AC_LANG_SOURCE.
zlib:
Merge from GCC.
PR bootstrap/82856
* Makefile.am: Include multilib.am.
* Makefile.in: Regenerate.