From: Daniel Drake <d.drake@mmm.com>

Allow build flags to be pulled from the environment, and make this the default
behaviour (but fall back on old defaults if environment is empty).

Index: acgmake/bin/acgmake
===================================================================
--- acgmake.orig/bin/acgmake
+++ acgmake/bin/acgmake
@@ -68,7 +68,7 @@ done
 
 
 # parse options
-CODE_LEVEL=dbg
+CODE_LEVEL=default
 LIB_TYPE=shared
 HIDE="@"
 JOBS=""
@@ -79,6 +79,7 @@ for i in $OPTIONS ; do
 
 
     # compilation options
+    -env )  CODE_LEVEL=env ;;
     -dbg )  CODE_LEVEL=dbg ;;
     -prf )  CODE_LEVEL=prf ;;
     -opt )  CODE_LEVEL=opt ;;
@@ -174,6 +175,13 @@ if [ $? != 0 ] ; then 
 fi
 ARCH=`$ACGMAKE/bin/arch.sh`
 
+# if no compiler options were specified, attempt to pull cflags out of
+# environment, and fallback on dbg if none were specified
+if [ "$CODE_LEVEL" == "default" -a -z "$CXXFLAGS" -a -z "$CXXDEFS" -a -z "$LDFLAGS" ]; then
+    CODE_LEVEL="dbg"
+else
+    CODE_LEVEL="env"
+fi
 
 
 # collect options
Index: acgmake/modules/cxx_include
===================================================================
--- acgmake.orig/modules/cxx_include
+++ acgmake/modules/cxx_include
@@ -153,9 +153,17 @@ ifneq ($(PACKAGES),)
 endif
 
 
-CXX_DEFS    += $(CXX_DEFS_$(call uppercase,$(CODE_LEVEL)))
-CXX_CFLAGS  += $(CXX_CFLAGS_$(call uppercase,$(CODE_LEVEL)))
-CXX_LDFLAGS += $(CXX_LDFLAGS_$(call uppercase,$(CODE_LEVEL)))
+ifeq ($(CODE_LEVEL),env)
+  # these come from the environment
+  CXX_DEFS    += $(CXXDEFS)
+  CXX_CFLAGS  += $(CXXFLAGS)
+  CXX_LDFLAGS += $(LDFLAGS)
+else
+  CXX_DEFS    += $(CXX_DEFS_$(call uppercase,$(CODE_LEVEL)))
+  CXX_CFLAGS  += $(CXX_CFLAGS_$(call uppercase,$(CODE_LEVEL)))
+  CXX_LDFLAGS += $(CXX_LDFLAGS_$(call uppercase,$(CODE_LEVEL)))
+endif
+
 CXX_CFLAGS  += $(CXX_DEFS)
 CXX_CFLAGS  += $(cxx-cflags)
 CXX_CFLAGS  += $(cxx-incpath)