C library check: do not warn about the need for MMX

We provide stubs of some MMX functions. Our use of them, however, is not
conditional on MMX being enabled. No need for GCC to warn about this.

Fixes: diffblue#8049

src/ansi-c/library_check.sh

@@ -15,7 +15,7 @@ for f in "$@"; do
     $CC -std=gnu11 -E -include library/cprover.h -D__CPROVER_bool=_Bool -D__CPROVER_thread_local=__thread -DLIBRARY_CHECK -o __libcheck.i __libcheck.c
     $CC -S -Wall -Werror -pedantic -Wextra -std=gnu11 __libcheck.i \
       -o __libcheck.s -Wno-unused-label -Wno-unknown-pragmas \
-      -Wno-gnu-line-marker -Wno-unknown-warning-option
+      -Wno-gnu-line-marker -Wno-unknown-warning-option -Wno-psabi
     ec="${?}"
     rm __libcheck.s __libcheck.i __libcheck.c
     [ "${ec}" -eq 0 ] || exit "${ec}"