Remove misleading line from dx.jar Android.mk file.

Previously we had a line in the dx.jar Android.mk file that indicates
that dx.jar is compiled with java 1.6. This was a lie and it has been
being compiled with java 1.8 for quite a while.

Bug: 28464522
Change-Id: Idc21295d7aca6afced16c46c16951a4aa66535d0
diff --git a/dx/src/Android.mk b/dx/src/Android.mk
index b9673db..248f854 100644
--- a/dx/src/Android.mk
+++ b/dx/src/Android.mk
@@ -18,10 +18,6 @@
 LOCAL_MODULE_TAGS := optional
 LOCAL_MODULE:= dx
 
-# Force java 6 target because we want java 6 runtimes to run dx, at least as long as the android SDK
-# requirement JDK 6.
-LOCAL_JAVACFLAGS:= -source 6 -target 6
-
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 INTERNAL_DALVIK_MODULES += $(LOCAL_INSTALLED_MODULE)