diff -r 8ab1a1ee2af6 -r d509ae946997 make/autoconf/flags.m4
--- a/make/autoconf/flags.m4	Mon Feb 26 09:56:12 2018 +0100
+++ b/make/autoconf/flags.m4	Mon Feb 26 10:19:03 2018 +0100
@@ -27,6 +27,13 @@
 m4_include([flags-ldflags.m4])
 m4_include([flags-other.m4])
 
+# Sort the flags in a given variable, and remove superfluous whitespace.
+#
+# $1 = name of variable to sort
+AC_DEFUN([FLAGS_SORT_FLAGS], [
+  $1=`$ECHO ${$1} | $TR ' ' '\n' | $SORT | $TR '\n' ' '`
+])
+
 ################################################################################
 #
 # Setup ABI profile (for arm)