put back default optimization to -O6 (previously changed by mistake)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89334 65c4cc65-6c06-0410-ace0-fbb531ad65f3

Makefile.rules

@@ -38,7 +38,7 @@ ifeq ($(findstring DONT_OPTIMIZE,$(MENUSELECT_CFLAGS)),)
     # ppro's, etc, as well as the AMD K6 and K7.  
     #K6OPT=-DK6OPT
 
-    OPTIMIZE?=-O2
+    OPTIMIZE?=-O6
     ASTCFLAGS+=$(OPTIMIZE)
 endif