verison-handler: Cleanup extern C

We want to make sure the definition and declaration names match, and
don't need to separate them. Using extern "C" for one and not the other
could cause them to mismatch otherwise.

Change-Id: I67058edec66404108e68bbb4cb3768622077e057
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/bmc/version-handler/main.cpp b/bmc/version-handler/main.cpp
index aae27f7..7b21152 100644
--- a/bmc/version-handler/main.cpp
+++ b/bmc/version-handler/main.cpp
@@ -75,12 +75,8 @@
     return handler;
 }
 } // namespace ipmi_flash
-extern "C"
-{
-    std::unique_ptr<blobs::GenericBlobInterface> createHandler();
-}
 
-std::unique_ptr<blobs::GenericBlobInterface> createHandler()
+extern "C" std::unique_ptr<blobs::GenericBlobInterface> createHandler()
 {
     ipmi_flash::VersionHandlersBuilder builder;
     return ipmi_flash::createHandlerFromJsons(