Test the compiler configuration, not the assembler

With gcc-4.4 at least, the raw asm.s files will always successfully
compile even if the default -march for the compiler would not support
those instructions.  So switch to testing the inline asm versions,
where the compiler will barf if they aren't supported by the default
arch if no -march is explicitly given, or if they aren't supported by
the requested -march when it is.