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 needed by vogar to 1.7.

Bug: 26753820
Bug: 27310428
(cherry picked from commit 6a66412ab9c544ca7e099f81e764d2c01671ea70)

Change-Id: I0788ba7636f7cb6ab75f4efd42ed21a3a00a39e8
diff --git a/Android.mk b/Android.mk
index ee45b62..cb402a8 100644
--- a/Android.mk
+++ b/Android.mk
@@ -46,6 +46,7 @@
 PROCESSOR_CLASSES := $(DAGGER2_PROCESSOR_CLASSES)
 include external/dagger2/java_annotation_processors.mk
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # Remember the location of the generated files, this is needed for when
@@ -68,6 +69,7 @@
   caliper/src/main/java/com/google/caliper/All.java \
   caliper/src/main/java/com/google/caliper/Benchmark.java
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_JAVA_LIBRARY)
 
 # build caliper tests
@@ -96,6 +98,7 @@
 PROCESSOR_CLASSES := $(DAGGER2_PROCESSOR_CLASSES)
 include external/dagger2/java_annotation_processors.mk
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # build caliper examples
@@ -114,6 +117,7 @@
   junit \
   mockito-host
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.7
 include $(BUILD_HOST_JAVA_LIBRARY)
 
 # Build host dependencies.