Fix build.gradle

Change-Id: I512d91fd7dc8842b8480a7a91761217e92eff3bd
diff --git a/build.gradle b/build.gradle
index 5181fbd..a0ff782 100644
--- a/build.gradle
+++ b/build.gradle
@@ -176,7 +176,7 @@
         println 'Build failed. Possible causes include:'
         println '    1) Bad codes'
         println '    2) Out of date prebuilts in prebuilts/sdk'
-        println '    3) Need to update the compileSdkVersion in a library's build.gradle'
+        println '    3) Need to update the compileSdkVersion in a library\'s build.gradle'
         println()
     }
 }