Log message:
*: Assume that the user has a C99-capable compiler.

A compiler that supports -std=c99 is required for
bootstrap, so it doesn't make sense to specify a c99
compiler everywhere in package makefiles.

At any rate, I would bet my entire life's savings that
this is a small fraction of the total number of packages
requiring c99.

Note that compilers that default to c89 but support c99
are still supported...

Log message:
lang/gcc6: Add scary comment over GCC_TARGET_MACHINE substitution.

Same one as in later lang/gcc* versions, for consistency.

No functional change intended.

Log message:
gcc6: specify -Wno-missing-attributes only on newer gcc versions.

This makes stage1 gcc builds on Mac OS Tiger with Xcode 2.5 (gcc 4.0.1)
but still fails during stage2 libstdc++.

Log message:
gcc*: Add NOT_FOR_PLATFORM for Darwin/aarch64.

None of these releases support that platform, at least not without a large
patch like the one we currently use for lang/gcc12 (to provide gfortran).

Log message:
gcc*: fix variable comparison

From RVP in PR 57998.

Log message:
gcc6: can't work on NetBSD/aarch64

Log message:
gcc*: include missing header and unbreak build on Linux.

Log message:
gcc*: Disable FORTIFY on Linux only

Log message:
lang/gccX: switch from USE_LANGUAGES=c99 to USE_CC_FEATURES/FORCE_C_STD.

Log message:
gcc*: replace gnarly cargo-culted extract logic with EXTRACT_ONLY