Honour CFLAGS and DEBUG.

Index: Makefile-gcc
--- Makefile-gcc.orig
+++ Makefile-gcc
@@ -38,15 +38,8 @@ CFLAGS := -Ipub -Ipriv \
 	-Wwrite-strings -Wformat -Wformat-security \
 	-std=gnu99 -fstrict-aliasing -fPIC \
 	-DPYVEX \
-	$(EXTRA_CFLAGS)
+	$(CFLAGS)
 
-# If not debugging, put -g -O2 after any flags we inherit from our invoker
-# -O2 vs -O makes a significant difference, at least with gcc4
-ifeq ($(DEBUG),1)
-CFLAGS += -g
-else
-CFLAGS += -O2
-endif
 
 # These are a separate set of defines that compile for parallel environments
 #CC = icc