Building libcore in master is spam city. Fix that.

Actually, this is more of a workaround. The real fix would be:

1. work out why @SuppressWarnings("unchecked") isn't working.
2. move the XML crap (which we're not maintaining, and where we don't fix
   warnings) out into external/.
3. uncomment the commented-out line in this patch.

(I've fixed our real non-"unchecked" warnings in earlier patches.)

Change-Id: I5a2dcb071eef5b46c8f166f9492d56cfdb5c6fa5
diff --git a/JavaLibrary.mk b/JavaLibrary.mk
index 68f93d2..e954f99 100644
--- a/JavaLibrary.mk
+++ b/JavaLibrary.mk
@@ -59,6 +59,9 @@
     core_resource_dirs += ../external/emma/core/res ../external/emma/pregenerated/res
 endif
 
+local_javac_flags=-encoding UTF-8
+#local_javac_flags+=-Xlint:all -Xlint:-serial,-deprecation,-unchecked
+local_javac_flags+=-Xmaxwarns 9999999
 
 #
 # Build for the target (device).
@@ -72,7 +75,7 @@
 LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
 
 LOCAL_NO_STANDARD_LIBRARIES := true
-LOCAL_JAVACFLAGS := -encoding UTF-8
+LOCAL_JAVACFLAGS := $(local_javac_flags)
 LOCAL_DX_FLAGS := --core-library
 
 LOCAL_NO_EMMA_INSTRUMENT := true
@@ -264,7 +267,7 @@
     LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
 
     LOCAL_NO_STANDARD_LIBRARIES := true
-    LOCAL_JAVACFLAGS := -encoding UTF-8
+    LOCAL_JAVACFLAGS := $(local_javac_flags)
     LOCAL_DX_FLAGS := --core-library
 
     LOCAL_NO_EMMA_INSTRUMENT := true