(nobuild) Build script doesn't support additional compiler flags

[zhiayang]

On some platforms (cough old-ass Solaris cough), the C compiler might default to generating 32-bit code, which obviously doesn't work for bm. Ideally, we would be able to do something like this:

CC="cc -m64" nobuild test

but that won't work, because nobuild passes the entire string "cc -m64" to execvp, which obviously doesn't exist.

[rexim]

@zhiayang oh! Thank you for reporting this use case! I'll see what we can do about it!