Disable gcc-4.6's Wunused-but-set-variables warning.

Change-Id: Ia02fa536410b9200beca1d9d120ec448c82e5ca8
diff --git a/core/config.mk b/core/config.mk
index 82238e9..3a25825 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -102,6 +102,11 @@
 # list of flags to turn specific warnings in to errors
 TARGET_ERROR_FLAGS := -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point
 
+# Temporarily turn off Wunsed-but-set-variables warning in gcc-4.6
+# since this warning becomes an error in dalvik, core and renderscript.
+# This is ignored by gcc-4.4.x.
+TARGET_ERROR_FLAGS += -Wno-unused-but-set-variable
+
 # TODO: do symbol compression
 TARGET_COMPRESS_MODULE_SYMBOLS := false