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/build.gradle b/compat/build.gradle
index 5722998..696c321 100644
--- a/compat/build.gradle
+++ b/compat/build.gradle
@@ -44,6 +44,7 @@
                 'api22',
                 'api23',
                 'api24',
+                'api26',
                 'java'
         ]
         main.aidl.srcDirs = ['java']