Optimize GL emulation prepareClientAttributes. Fix issues where the slow path was not able to handle unaligned source data. Annotate some unsupported cases. Remove liveClientAttributes, which does not seem to be a win in profiles.
Update to current libcxxabi for new exception code.
Update libcxx to current version.
Missing string.h functionality.
Handle negative zero values correctly.

This handles the situation when they're part of a global variable
whether it just be a float/double or embedded within a struct.

Fixes #1898.
Reintroduce liveClientAttributes to optimize the case where GL emulation code is called with a very large GLImmediate.MAX_TEXTURES size.
Merge pull request #1999 from juj/gl_prepareclientattr

GL prepareClientAttributes.
remove old test that cannot be done in fastcomp, relies on code miscompilation in original compiler
fix testcase to validate as llvm ir
clean up some more tests/cases
add dependencies so code with exceptions (invoke/landingpad) but without an actual throw will still pull in the necessary stuff
Add strtod(), wcstod(), wcstol() and friends.

This implementation of strtod() replaces the old as it implements
support for parsing hex constants which is needed by various tests.
Add gamma functions.
Make lgamma and friends work, add test.

We can't use weak aliases on variables in emscripten, so get rid of __signgam
and just use signgam.
Another test for negative zero and hex floats.
Add lots of math functions.
Move scalbn to libc to fix broken functionality. Disable test on x86.
Bump version.
allow relooper to manager its own output buffer, to avoid fixed output limits
avoid leaks on multiple calls to relooper MakeOutputBuffer