Merge branch 'prog-cc-c-o-work' into maint * prog-cc-c-o-work: tests: some tests make no sense if "$CC -c -o" doesn't work AM_PROG_CC_C_O: don't rely on AC_PROG_CC_C_O, re-implement similar logic compile: rewrite AC_PROG_CC with AM_PROG_CC_C_O contents