Clang has fully implemented OpenMP support as of LLVM 3.7, so if OpenMP
is required by a formula gcc is no longer the only choice of compiler.
Clang should be preferred over gcc because using gcc meant linking
against libstdc++, which is ABI incompatible with libc++. This may be
unnoticeable for some users, but it causes other builds to fail, e.g.
pstoedit when imagemagick was built with OpenMP. pstoedit is required
for the octave formula, so for some users this could be a significant
problem.
`-Wl,-z,defs` should be pruned out entirely since `-z defs` is not
understood by macOS's `ld`, and the analogue `-undefined error` is
already the default.
Not quite a mass replacement as I've used OS X and Mac OS X where
describing specific older versions and added compatibility methods
for things in the DSL.
/usr/local/lib is removed from the default linker search path when
SDKROOT is defined or sysroot is specified.
Homebrew sometimes sets SDKROOT without setting a sysroot as of 45e138f.
Move some stuff formerly in `Library/ENV` around:
- Move `Library/ENV/$XCODE_VERSION` to `Library/Homebrew/env/super` as they are
all superenv wrappers and all symlinks to the same version. We never needed
the "separate shims for separate versions" functionality and it just adds
confusion.
- Move `Library/ENV/pkgconfig` to `Library/Homebrew/env/pkgconfig` to get more
things under `Library/Homebrew`
- Move `Library/ENV/scm` to `Library/scm` as these wrappers are not actually
used by or related to superenv (or stdenv) in any way.
