Bake in the product name into the StartupOptions classes.

Now that we have gotten a StartupOptions class for each of the products
we support, we can bake in the product name in each instance instead of
passing it to the constructor.  Helps with encapsulation and simplifies
various instantiations of these classes.

--
MOS_MIGRATED_REVID=133255854
diff --git a/src/main/cpp/startup_options.cc b/src/main/cpp/startup_options.cc
index b3a8afc9..5d3e9f4 100644
--- a/src/main/cpp/startup_options.cc
+++ b/src/main/cpp/startup_options.cc
@@ -33,6 +33,11 @@
 
 using std::vector;
 
+StartupOptions::StartupOptions() :
+  StartupOptions("Bazel") {
+  Init();
+}
+
 StartupOptions::StartupOptions(const string& product_name) :
   product_name(product_name) {
   Init();