other compilers don't need this option, but gcc 3 and perhaps others accept it despite not understanding it, then print warnings about it at build time. omitting it when not needed will also help shorten the command lines.
@@ -507,7 +507,7 @@ tryflag CFLAGS_AUTO -Werror=pointer-arith
# parameter to stop printing warnings about LDFLAGS passed during
# compiling stage and CFLAGS passed during linking stage.
#
-tryflag CFLAGS_AUTO -Qunused-arguments
+test "$cc_family" = clang && tryflag CFLAGS_AUTO -Qunused-arguments
if test "x$warnings" = xyes ; then
tryflag CFLAGS_AUTO -Wall
Rich Felker