Update protoc dep to 3.0.0 (#1958)

pending_code_changes.txt

@@ -1,2 +1,5 @@
 Build changes:
  - C++ geocoding build tools now use readdir, since readdir_r is deprecated.
+ - Update the protobuf-java dependency used to build the C++ metadata from 2.5.0
+   to 3.0.0. This is an internal change and does not affect the users of the
+   library.

tools/java/cpp-build/pom.xml

@@ -153,7 +153,7 @@
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>2.5.0</version>
+      <version>3.0.0</version>
     </dependency>
   </dependencies>