versioner: guard preprocessing messages with -v.

Bug: http://b/36751878
Test: tools/versioner/run_tests.py
Change-Id: I5142a33519b101548ccaec8a3bc498e446a648a7
diff --git a/tools/versioner/src/Preprocessor.cpp b/tools/versioner/src/Preprocessor.cpp
index 86bb225..2703842 100644
--- a/tools/versioner/src/Preprocessor.cpp
+++ b/tools/versioner/src/Preprocessor.cpp
@@ -409,7 +409,9 @@
     file_lines[loc.start.line - 1].insert(loc.start.column - 1, prologue);
   }
 
-  printf("Preprocessing %s...\n", output_path.c_str());
+  if (verbose) {
+    printf("Preprocessing %s...\n", output_path.c_str());
+  }
   writeFileLines(output_path, file_lines);
 }