Add build rule for Python dependency

Add lib rule to allow correct import of pyglib for G3

Change-Id: Icf0fadc7fee921cf9721b117084f2bd648bbea55
diff --git a/BUILD.extras b/BUILD.extras
index 4cb4803..aeb2ea1 100644
--- a/BUILD.extras
+++ b/BUILD.extras
@@ -73,6 +73,11 @@
 # These will be rewritten in Google3 to be dependencies on the real targets.
 
 perfetto_py_library(
+    name = "pyglib_noop",
+    srcs = [],
+)
+
+perfetto_py_library(
     name = "protobuf_noop",
     srcs = [],
 )
@@ -99,5 +104,6 @@
     deps = [
         ":protobuf_noop",
         ":protobuf_descriptor_pb2_noop",
+        ":pyglib_noop",
     ]
 )