* src/base/cl_low.h: Added several checks if NO_ASM is defined, so

    * src/base/cl_low.h: Added several checks if NO_ASM is defined, so
          this definition becomes actually useful.  This is needed for
          compilation on Arm until somebody fixes the assembler files for Arm.
        * src/base/digitseq/cl_asm.h: Likewise.
        * src/base/digitseq/cl_asm_.cc: Likewise.
        * */Makefile.in: Added `override' in front of `CPPFLAGS +=' so
           one can say `make CPPFLAGS=-DFOOBAR'.