ARM codegen: Add disassembler, implement return

This program works:

    main() { return 42; }

The disassembler was borrowed from codeflinger, and just modified enough to compile
under C++ without warnings.

Implemented gsym
Implemented a hack verison of li, only works for -256..255
Implemented gjmp
diff --git a/libacc/Android.mk b/libacc/Android.mk
index 30f777a..c3207cc 100644
--- a/libacc/Android.mk
+++ b/libacc/Android.mk
@@ -6,6 +6,7 @@
 #
 
 LOCAL_MODULE:= acc
-LOCAL_SRC_FILES := acc.cpp
+LOCAL_SRC_FILES := acc.cpp disassem.cpp
+LOCAL_MODULE_TAGS := tests
 
 include $(BUILD_EXECUTABLE)