Add libgtest_prod.

This is a header only library that can be used by modules that need
FRIEND_TEST. If used in a module's public headers, use
LOCAL_WHOLE_STATIC_LIBRARIES so that the module's users will also
have the headers available.

Bug: http://b/16574165
Change-Id: I09a87e44350f437acb74cb4298aa480bcc9748b7
diff --git a/src/Android.mk b/src/Android.mk
index 8763244..575f229 100644
--- a/src/Android.mk
+++ b/src/Android.mk
@@ -150,3 +150,17 @@
 
 include $(BUILD_STATIC_LIBRARY)
 endif
+
+# Header only libraries for modules that need gtest_prod.h. Libraries exporting
+# public headers that use gtest_prod.h should pull this in with
+# LOCAL_WHOLE_STATIC_LIBRARIES so that their users will also get the include
+# paths.
+include $(CLEAR_VARS)
+LOCAL_MODULE := libgtest_prod
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(libgtest_export_include_dirs)
+include $(BUILD_STATIC_LIBRARY)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libgtest_prod
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(libgtest_export_include_dirs)
+include $(BUILD_HOST_STATIC_LIBRARY)