gcc

• Disable bootstrap; stage1 is good enough
• Use a different libexecdir
• bootstrap-lto build configuration adjusts CFLAGS and LDFLAGS
• bootstrap-lto-lean has to be used with make profiledbootstrap
• bootstrap-debug-lean is slower and bigger compared to bootstrap-debug
• --enable-link-mutex has been deprecated, use --enable-link-serialization=1 instead: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109310 (=1 is sane, any higher value might thrash the system)
• cc1 depends on mpc at run time
• Depends on tar for the make target install-headers-tar
• As of 14.1, new configure options --enable-host-pie, to build the compiler executables as PIE; and --enable-host-bind-now, to link the compiler executables with -Wl,-z,now to enable additional hardening
• --enable-host-shared has a performance penalty on gcc