Pin libraries needed by vogar tool to java 1.7

vogar still uses javac/dx by default. dx does not
handle v52 class files. The default java version
is going to switch to 1.8. This change pins the
targets need by vogar to 1.7.

Bug: 26753820
Bug: 27310428
Change-Id: I0f18bc98d3500828a09dbe5a4766940ee993b9fe
diff --git a/Android.mk b/Android.mk
index cc57c5f..21fa4c1 100644
--- a/Android.mk
+++ b/Android.mk
@@ -28,6 +28,7 @@
   dagger2-inject-host \
   guavalib
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # build dagger2 producers host jar
@@ -45,6 +46,7 @@
   dagger2-inject-host \
   guavalib
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # build dagger2 compiler host jar
@@ -90,6 +92,7 @@
 
 include $(LOCAL_PATH)/java_annotation_processors.mk
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # Build host dependencies.