Adds jetifier plugin dependency into supportLib.

Test: N/A
Bug: b/64833662
Change-Id: I767101d9f72314827a581582a11194c7f3e49599
diff --git a/build.gradle b/build.gradle
index ec83da5..560bbda 100644
--- a/build.gradle
+++ b/build.gradle
@@ -25,6 +25,7 @@
     dependencies {
         classpath build_libs.gradle
         classpath build_libs.jacoco
+        classpath build_libs.jetifier
     }
 }
 
diff --git a/buildSrc/build_dependencies.gradle b/buildSrc/build_dependencies.gradle
index be135b9..13ff562 100644
--- a/buildSrc/build_dependencies.gradle
+++ b/buildSrc/build_dependencies.gradle
@@ -29,6 +29,7 @@
 build_libs.jarjar_gradle = 'org.anarres.jarjar:jarjar-gradle:1.0.0'
 build_libs.error_prone = 'net.ltgt.gradle:gradle-errorprone-plugin:0.0.13'
 build_libs.jacoco = 'org.jacoco:org.jacoco.core:0.7.8'
+build_libs.jetifier = 'androidx.tools.jetifier:gradle-plugin:0.1'
 build_libs.kotlin = [gradle_plugin: "org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.0"]
 
 rootProject.ext['build_libs'] = build_libs