Building Petrify

Build 32-bit SIS static libraries (see instruction) and put them into sis/lib directory:
- libsis32.a – 32-bit Linux build, gcc -m32 toolchain
- libsis32osx.a – 32-bit Mac OS X build, mp-gcc5 -m32 toolchain
- libsis32win.a - 32-bit Windows build, i686-w64-mingw32-gcc toolchain
Define the target operating system at the beginning of Makefile:
- OS = win – Windows
- OS = osx – Mac OS X
- OS = – Linux
Rebuild Petrify:
```
make clean  # optional
make
```

While 64-bit versions of Petrify can also be built, only the Linux 64-bit version is stable. If you decide to build a 64-bit version, then put libsis64.a of SIS library in sis directory and set ARCH=64 variable in the Makefile.