Enforce 64-bit build environment

We will only support 64-bit build environment beyond froyo/2.2 .

Change-Id: I71eb1230bf0bc12ccde2aeda6255db6a87540437

core/find-jdk-tools-jar.sh

@@ -3,7 +3,7 @@ if [ "x$ANDROID_JAVA_HOME" != x ] && [ -e "$ANDROID_JAVA_HOME/lib/tools.jar" ] ;
 else
     JAVAC=$(which javac)
     if [ -z "$JAVAC" ] ; then
-	echo "Please-install-JDK-5.0,-update-12-or-higher,-which-you-can-download-from-java.sun.com"
+	echo "Please-install-JDK-6,-which-you-can-download-from-java.sun.com"
 	exit 1
     fi
     while [ -L $JAVAC ] ; do

core/main.mk

@@ -60,12 +60,23 @@ include $(BUILD_SYSTEM)/config.mk
 # be generated correctly
 include $(BUILD_SYSTEM)/cleanbuild.mk
 
-VERSION_CHECK_SEQUENCE_NUMBER := 1
+VERSION_CHECK_SEQUENCE_NUMBER := 2
 -include $(OUT_DIR)/versions_checked.mk
 ifneq ($(VERSION_CHECK_SEQUENCE_NUMBER),$(VERSIONS_CHECKED))
 
 $(info Checking build tools versions...)
 
+ifeq ($(BUILD_OS),linux)
+build_arch := $(shell uname -m)
+ifneq (64,$(findstring 64,$(build_arch)))
+$(warning ************************************************************)
+$(warning You are attempting to build on a 32-bit system.)
+$(warning Only 64-bit build environments are supported beyond froyo/2.2.)
+$(warning ************************************************************)
+$(error stop)
+endif
+endif
+
 ifneq ($(HOST_OS),windows)
 ifneq ($(HOST_OS)-$(HOST_ARCH),darwin-ppc)
 # check for a case sensitive file system