This patch removes most of the settings for CC, CXX etc. because we are trying to be minimal. Then we force the compiler to Homebrew's choice underneath in superenv. We however leave LD because we prefer that build-systems use the c-compiler for linking, it generally works better (copiously tested), however when the build-system explicitly calls ld, we respect that. This gets around the ocaml bug in question, since somehow clang was crashing during link, but the ld tool itself (which is kind of clang, kind of llvm-gcc) is okay with this.
Also moved the setting of O (so that cc-args are refurbished) into a make wrapper. Not sure if this matter much, but seems more consistent.
Since we are moving towards only depending on X11 for X-headers, superenv now doesn't automatically add X11 compilation. I was reluctant to do this, but it is the right thing to do now that X11 is not automatically installed by OS X or Xcode.
I didn't implement ENV.x11 because the order that the X headers are inserted is important. It must be done at initial setup to ensure that brewed versions of e.g. freetype and Cairo are used and not the ones installed by XQuartz.
1. A minimal build environment, we don't set CFLAGS, CPPFLAGS, LDFLAGS, etc. the rationale being, the less that is set, the less variables we are introducing that can break builds.
2. A set of scripts that replace cc, ld, etc. and inject the -I, -L, etc. flags we need into the args passed to the build-tools.
Because we now have complete control over compiler instantiations we do a variety of clean-up tasks, like removing bad flags, enforcing universal builds and ensuring makefiles don't try to change the order of library and include paths from ones that work to ones that don't.
The previous ENV-system is still available when --env=std is specified.
superenv applies to Xcode >= 4.3 only currently.
