Fix support annotations build.gradle file

It pointed to the wrong source folder.

Change-Id: I973080c0ab7124d28a131a59be2811ac0c09fc72
diff --git a/annotations/build.gradle b/annotations/build.gradle
index 065bfb6..2ff9980 100644
--- a/annotations/build.gradle
+++ b/annotations/build.gradle
@@ -3,7 +3,7 @@
 archivesBaseName = 'support-annotations'
 
 sourceSets {
-    main.java.srcDir 'java'
+    main.java.srcDir 'src'
 }
 
 jar {