Configure check for -Wno-unused-parameter now tries to link too.

configure.in

@@ -1012,7 +1012,7 @@ if test x"$enable_acl_support" = x"no" -o x"$enable_xattr_support" = x"no" -o x"
     AC_MSG_CHECKING([whether $CC supports -Wno-unused-parameter])
     OLD_CFLAGS="$CFLAGS"
     CFLAGS="$CFLAGS -Wno-unused-parameter"
-    AC_COMPILE_IFELSE([ ], [rsync_warn_flag=yes], [rsync_warn_flag=no])
+    AC_TRY_LINK([#include <stdio.h>], [printf("hello\n");], [rsync_warn_flag=yes], [rsync_warn_flag=no])
     AC_MSG_RESULT([$rsync_warn_flag])
     if test x"$rsync_warn_flag" = x"no"; then
 	CFLAGS="$OLD_CFLAGS"