Created check for MACOSX with __MACH__

[exowanderer]

Inside all *.c files that the master branch version called #include <malloc.h> now checks if __MACH__ compiler flag exists. If it does, then the system is using OSX, which does not have the file /usr/local/include/malloc.h -- like linux does. Instead, the malloc command is containted inside stdlib.h.

By checking if the __MACH__ exists, and calling the correct malloc containing header file, the make command now correctly accesses the headers and creates the binary.

[exowanderer]

The Makefile that is listed as 'changed' is actually the identical Makefile.macosx that came with the original hotpants via github. I replaced it with Makefile before creating the binary. That can be ignored or overwritten later