Fix make install step when USE_THREAD=0

The OpenBLAS easyconfig potentially allows setting USE_THREAD=0 causing the "make install" step to fail if this is not passed to "make install". "make install" probably assumes USE_THREAD=1 regardless of what was specified in the "make" step. 

The generated library names are different: e.g. 
libopenblas_nehalemp.so
libopenblas_nehalem.so