Introduce ViewCompat.setTooltip

This calls View.setTooltip on API26+. The fallback
implementation is a Toast-based tooltip.

Use the new method in ActionMenuItemView,
MediaRouteButton, ScrollingTabContainerView and
TabLayout.

Bug: 31516506
Test: manual in Support7Demos and SupportDesignDemos
Change-Id: I23832a2fd5b589769225a0542c2a0ce4778e673c
diff --git a/compat/Android.mk b/compat/Android.mk
index ba5b958..9d8d258 100644
--- a/compat/Android.mk
+++ b/compat/Android.mk
@@ -42,6 +42,7 @@
     $(call all-java-files-under,api22) \
     $(call all-java-files-under,api23) \
     $(call all-java-files-under,api24) \
+    $(call all-java-files-under,api26) \
     $(call all-java-files-under,java) \
     $(call all-Iaidl-files-under,java)
 LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res