logcat: Add --regex option

You can now filter log output by a regex on the messages.

Test: New unit test passes
Bug: 27706081
Change-Id: Idfa637f62a25fb1b92e9b49b89572dff0fec6e08
diff --git a/logcat/Android.mk b/logcat/Android.mk
index b828a9f..1dacbe1 100644
--- a/logcat/Android.mk
+++ b/logcat/Android.mk
@@ -5,7 +5,7 @@
 
 LOCAL_SRC_FILES:= logcat.cpp event.logtags
 
-LOCAL_SHARED_LIBRARIES := liblog libbase libcutils
+LOCAL_SHARED_LIBRARIES := liblog libbase libcutils libpcrecpp
 
 LOCAL_MODULE := logcat