stlviewer shows a 3d representation of stl files

Closes #19196.

Signed-off-by: Xiyue Deng <manphiz@gmail.com>
gpg-agent 2.0.21
gnupg2 2.0.21
macvim: use std env on Snow Leopard

Closes #21639.
calc 2.12.4.8/2.12.4.10
superenv: fix CC value for ENV.gcc

'gcc' could refer to anything of llvm-gcc, clang, or gcc-4.0 on
various Xcode versions.