break up event-log-tags; generate java source files with constants

Construct the /system/etc/event-log-tags file by unioning together any
*.logtags files included in LOCAL_SRC_FILES throughout the system (with
appropriate error checking for dup tag numbers, etc.)

For java packages, generate a java source file from the logtags file for
that package that contains static integer constants for each tag name.
diff --git a/core/config.mk b/core/config.mk
index e574124..586f403 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -201,6 +201,7 @@
 E2FSCK := e2fsck
 JARJAR := java -jar $(HOST_OUT_JAVA_LIBRARIES)/jarjar.jar
 PROGUARD := external/proguard/bin/proguard.sh
+JAVATAGS := build/tools/java-event-log-tags.py
 
 # dx is java behind a shell script; no .exe necessary.
 DX := $(HOST_OUT_EXECUTABLES)/dx
@@ -295,7 +296,6 @@
 
 PREBUILT_IS_PRESENT := $(if $(wildcard prebuilt/Android.mk),true)
 
-
 # ###############################################################
 # Collect a list of the SDK versions that we could compile against
 # For use with the LOCAL_SDK_VERSION variable for include $(BUILD_PACKAGE)