Fix library name and installation path

Name of the library does not depend on type off compilation
(native or cross-compilation) and even does not depend on
architecture. Library installation directory name suffix is used
correctly (instad of using it as library suffix).
Merge pull request #12 from pinkavaj/fix_64-03

Fix library name and path on some 64bit systems
Adding artih.h for Cortex M4 cross-compile
Generated by running artihchk.c on Piksi. See piksi_firmware/tests/arithchk.
Update build system to not compile BLAS/LAPACK etc with code coverage
Merge pull request #20 from fnoble/fix_coverage

Update build system to not compile BLAS/LAPACK etc. with code coverage