Reduce call chain of qsort

This will considerably improve the performance of qsort-heavily-used projects
like Android-Pinyin-IME, more discussion:
  https://groups.google.com/forum/#!topic/emscripten-discuss/Ah2CNfQ8ra4
  https://github.com/kripken/emscripten/pull/1437
absolutize and verify paths in the file packager
added addOnPreRun and addOnPostRun
do not emit -m32 when using le32 target
only emit -nostdinc++ when calling clang to build a file ending in a cpp-style suffix
Use switch statement for isspace implementation. Results in huge speed increase on Chrome Android at least, avoiding a hot path in common tasks like XML parsing, etc.
Merge pull request #1455 from j4m3z0r/fast_isspace

Use switch statement for isspace implementation. Results in huge speed i...
Merge pull request #1452 from inolen/onprerun

added addOnPreRun and addOnPostRun
do not use -nostdinc++ with le32 target at all, it does not need it, and add testing for no system c++ headers showing up in our path
Merge branch 'qsort_reduce_callchain' of github.com:PinZhang/emscripten into incoming
optimize bsearch
refactor asm module parsing code into separate file
add tools to split and merge asm modules from the surrounding code
split up FS.init