Fix: Correct the order of AX_APPEND_COMPILE_FLAGS

configure.ac

@@ -20,11 +20,11 @@ AS_IF([test "${ac_cv_prog_cc_c99}" = "no"], [
   AC_MSG_ERROR([No C99 compiler found!])
 ])
 
-AX_APPEND_COMPILE_FLAGS([-Wall -Wextra -Wno-unused-parameter])
-
 dnl With clang, we want an error for unknown flags instead of just warn
 AX_APPEND_COMPILE_FLAGS([-Werror=unknown-warning-option -Werror=invalid-command-line-argument])
 
+AX_APPEND_COMPILE_FLAGS([-Wall -Wextra -Wno-unused-parameter])
+
 AC_SYS_LARGEFILE
 AC_DEFINE([_GNU_SOURCE], 1, [Define to include GNU extensions to POSIX])