asterisk-chan-dongle: add patch to force OpenWrt CFLAGS

Prevent ./configure from adding '-O6' to CFLAGS.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

net/asterisk-chan-dongle/patches/300-use-openwrt-flags.patch

@@ -0,0 +1,11 @@
+--- a/configure.ac
++++ b/configure.ac
+@@ -216,8 +216,6 @@ dnl Apply options to defines
+ if test "x$enable_debug" = "xyes" ; then
+   CFLAGS="$CFLAGS -O0 -g"
+   AC_DEFINE([__DEBUG__], [1], [Build with debugging])
+-else
+-  CFLAGS="$CFLAGS -O6"
+ fi
+ 
+ dnl Asterisk header files use lots of old style declarations, ignore those.