Restore PDX support to atrace.

Restore PDX service tracing in atrace. This time only enable poking PDX services
when the "pdx" trace category is included.

Bug: 62882199
Test: Run systrace with/without pdx category and observe correct poke behavior.

Change-Id: I478332a661c3b8bc6061fda43f64b75d8113b305
diff --git a/cmds/atrace/Android.bp b/cmds/atrace/Android.bp
index 5548699..abf7b06 100644
--- a/cmds/atrace/Android.bp
+++ b/cmds/atrace/Android.bp
@@ -14,6 +14,9 @@
         "libz",
         "libbase",
     ],
+    static_libs: [
+        "libpdx_default_transport",
+    ],
 
     init_rc: ["atrace.rc"],