Move buildSrc classes to androidx.build package.

Test: ./gradlew assembleDebug for support and flatfoot projects
Change-Id: I9ecada2082209e46058dbce453d7222d3999c925
diff --git a/dynamic-animation/build.gradle b/dynamic-animation/build.gradle
index 451e874..04d3c33 100644
--- a/dynamic-animation/build.gradle
+++ b/dynamic-animation/build.gradle
@@ -1,6 +1,6 @@
-import static android.support.dependencies.DependenciesKt.*
-import android.support.LibraryGroups
-import android.support.LibraryVersions
+import static androidx.build.dependencies.DependenciesKt.*
+import androidx.build.LibraryGroups
+import androidx.build.LibraryVersions
 
 plugins {
     id("SupportAndroidLibraryPlugin")