Fix build on OS X
Fix build on OS X

On OS X the malloc header is inside /usr/include/malloc. Add that to the
include paths instead of changing the code to conditionally include
`malloc/malloc.h`.

uname_S is taken from git's Makefile [1]

  [1]: http://git.kernel.org/cgit/git/git.git/tree/Makefile

zcsteele/turbo,YuanPeir-Chen/turbo-support-mipsel,luastoned/turbo,mniestroj/turbo,luastoned/turbo,kernelsauce/turbo,ddysher/turbo,zcsteele/turbo,YuanPeir-Chen/turbo-support-mipsel,ddysher/turbo