alac: style nit
aplus: style nit
autoenv: style nits
basex: install metafiles in prefix
botan: simplify

* don't need to_s on ENV.compiler
* soname inreplace no longer needed
chcase: style nits
superenv: find Homebrew's gcc-4.2

If we're using a homebrewed gcc-4.2, xcrun may fail to find it (or,
worse, find superenv's shim instead). Explicitly add it to the PATH and
search all path elements for the requested tool.

Also make sure to specify 'gcc-4.2' as the compiler name, not plain
'gcc'. That can resolve to llvm-gcc and to gcc-4.0 on various Xcodes.