JRuby 1.6.7.2 cext build on Mountain Lion not working through RVM

gistfile1.diff

diff --git a/cext/src/Makefile b/cext/src/Makefile
index 1622165..5f9ff3e 100644
--- a/cext/src/Makefile
+++ b/cext/src/Makefile
@@ -154,7 +154,7 @@ endif
 
 ifeq ($(OS), darwin)
   PLATFORM = Darwin
-  MACSDK = $(firstword $(filter-out %/MacOSX10.4u.sdk, $(wildcard /Developer/SDKs/MacOSX*.sdk)))
+  MACSDK = $(lastword $(filter-out %/MacOSX10.4u.sdk, $(shell find $(shell xcode-select -print-path) -name 'MacOSX10.*.sdk')))
   JDK_INCLUDES = -I$(MACSDK)/System/Library/Frameworks/JavaVM.framework/Headers
   ARCHES = ppc
   ifneq ($(findstring $(CPU), i386 x86_64),)
@@ -169,6 +169,8 @@ ifeq ($(OS), darwin)
   #CFLAGS += -I$(MACSDK)/System/Library/Frameworks/Kernel.framework/Versions/A/Headers
   PICFLAGS =
   SOFLAGS =
+  CXX = g++
+  CC = gcc
 endif
 
 ifeq ($(OS), linux)