vm: optionally set CC and CXX on macosx.

vm/Config.linux

@@ -5,6 +5,6 @@ LIBS = -ldl -lm -lrt -lpthread $(X11_UI_LIBS) -Wl,--export-dynamic
 
 # clang spams warnings if we use -Wl,--no-as-needed with -c
 # -Wl,--no-as-needed is a gcc optimization, not required
-ifneq ($(CPP),clang++)
+ifneq ($(CXX),clang++)
 	SITE_CFLAGS += -Wl,--no-as-needed
 endif

vm/Config.macosx

@@ -16,7 +16,7 @@ else
 	LIBS = -lm -framework Cocoa -framework AppKit
 endif
 
-LINKER = $(CPP) $(CFLAGS) -dynamiclib -single_module \
+LINKER = $(CXX) $(CFLAGS) -dynamiclib -single_module \
 	-current_version $(VERSION) \
 	-compatibility_version $(VERSION) \
 	-fvisibility=hidden \
@@ -28,12 +28,12 @@ LEOPARD_P := $(shell [[ `uname -r | sed -E -e 's/^([0-9]+).*/\1/'` -le 9 ]]; ech
 XCODE_4_P := $(shell [[ `xcodebuild -version | sed -E -ne 's/^Xcode ([0-9]+).([0-9]).*/\1\2/p'` -ge 43 ]]; echo $$?)
 
 ifeq ($(LEOPARD_P),0)
-	CC = gcc-4.2
-	CPP = g++-4.2
+	CC ?= gcc-4.2
+	CXX ?= g++-4.2
 endif
 
 ifeq ($(XCODE_4_P),0)
-	CC = clang
-	CPP = clang++
+	CC ?= clang
+	CXX ?= clang++
 endif