Add standard Android logging to aidl

This greatly helps understanding the code by enabling instrumenting
with debug logging statements.  To use:

ANDROID_LOG_TAGS=*:v aidl ....

Will cause the logging to log at the verbose level.  See base/logging.h
for more tricks.

Change-Id: I44ec26374419ca9d575f14b65c422444d17fcc66
Test: Ran the example command saw verbose logging.
diff --git a/main.cpp b/main.cpp
index 7fc4193..f4c1911 100644
--- a/main.cpp
+++ b/main.cpp
@@ -18,11 +18,14 @@
 #include <memory>
 
 #include "aidl.h"
+#include "logging.h"
 #include "options.h"
 
 using android::aidl::Options;
 
-int main(int argc, const char** argv) {
+int main(int argc, char** argv) {
+  android::base::InitLogging(argv);
+  LOG(DEBUG) << "aidl starting";
   std::unique_ptr<Options> options = Options::ParseOptions(argc, argv);
   if (!options) {
     return 1;