Change-Id: Ic896276cd073d6b41930c7c5a29d66348cd1725d

Without specifying thread count, NUM_THREADS would not be defined and CMake would fail.
This is because core count cannot be determined when cross-compiling.

Fix typos and bad if statements discovered in 0.2.20.

Add support for not having host compiler as CMake cannot detect such a compiler.
Add support for not using getarch.
Successfully builds Android ARMV8. Any target can be added by supplying the TARGET_CORE config in prebuild.cmake.

If OpenBLAS is built using add_subdirectory(OpenBlas) as part of another project
then the paths set by CMAKE_XXX_DIR are relative to the parent project
and not the OpenBLAS project.

e.g. Build 32-bit on 64-bit Linux.
cmake -DBINARY=32

Disable CBLAS and LAPACK.

This will generate obj files for SINGLE/DOUBLE/COMPLEX/DOUBLE COMPLEX.

Fixed some typos.

Updated c_check to set ARCH and BINARY64/32.

Added version variables.

Still isn't parsed into CMake variables, and getarch_2 needs to
get the same treatment.

It only does the double precision compile currently.

I realized I didn't finish converting Makefile.system yet, so I made
a note of that.