Add support for ALTERNATE_JAVAC

Bug: 12476356
Change-Id: Idd013031dc32a560bca76cca295bedcad55982b4
diff --git a/core/combo/javac.mk b/core/combo/javac.mk
index 2aea3e1..cc2c872 100644
--- a/core/combo/javac.mk
+++ b/core/combo/javac.mk
@@ -3,6 +3,7 @@
 # Inputs:
 #	CUSTOM_JAVA_COMPILER -- "eclipse", "openjdk". or nothing for the system 
 #                           default
+#	ALTERNATE_JAVAC -- the alternate java compiler to use
 #
 # Outputs:
 #   COMMON_JAVAC -- Java compiler command with common arguments
@@ -14,13 +15,19 @@
 common_flags := -source 1.7 -target 1.7 -Xmaxerrs 9999999
 endif
 
+# Use the indexer wrapper to index the codebase instead of the javac compiler
+ifeq ($(ALTERNATE_JAVAC),)
+JAVACC := javac
+else
+JAVACC := $(ALTERNATE_JAVAC)
+endif
 
 # Whatever compiler is on this system.
 ifeq ($(BUILD_OS), windows)
     COMMON_JAVAC := development/host/windows/prebuilt/javawrap.exe -J-Xmx256m \
         $(common_flags)
 else
-    COMMON_JAVAC := javac -J-Xmx512M $(common_flags)
+    COMMON_JAVAC := $(JAVACC) -J-Xmx512M $(common_flags)
 endif
 
 # Eclipse.
@@ -32,6 +39,6 @@
 
 HOST_JAVAC ?= $(COMMON_JAVAC)
 TARGET_JAVAC ?= $(COMMON_JAVAC)
-    
+
 #$(info HOST_JAVAC=$(HOST_JAVAC))
 #$(info TARGET_JAVAC=$(TARGET_JAVAC))