Add external/google-benchmark to the manifest.

Change-Id: Ibe585e8811c647664a5935d898615ebcd4316236
diff --git a/default.xml b/default.xml
index cb65d18..c013215 100644
--- a/default.xml
+++ b/default.xml
@@ -134,6 +134,7 @@
   <project path="external/giflib" name="platform/external/giflib" groups="pdk,qcom_msm8x26" />
   <project path="external/glide" name="platform/external/glide" groups="pdk-fs" />
   <project path="external/gmock" name="platform/external/gmock" groups="pdk" />
+  <project path="external/google-benchmark" name="platform/external/google-benchmark" groups="pdk" />
   <project path="external/google-breakpad" name="platform/external/google-breakpad" groups="dragon" />
   <project path="external/google-fonts/carrois-gothic-sc" name="platform/external/google-fonts/carrois-gothic-sc" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/google-fonts/coming-soon" name="platform/external/google-fonts/coming-soon" groups="pdk-cw-fs,pdk-fs" />