RFC: Fix various problems with "printf" and warnings

[Jim Blandy]

Awesome.  That doesn't look like a terribly entertaining bit of work.  :)

Should we be using sed s/...//g?

I guess this patch shouldn't address such issues, but those Makefile
variable names are pretty wild.  The 'CFLAGS' lexeme sometimes appears
in the middle, sometimes at the end; we use 'INTERNAL' and 'GDB' to
mean essentially the same thing; and it seems sometimes we just drop
that altogether.