Move versioning to a static library to improve trivial build speed (bug 5997 part 9, r=ds).

extensions/curl/extension.cpp

@@ -78,11 +78,11 @@ void CurlExt::SDK_OnUnload()
 
 const char *CurlExt::GetExtensionVerString()
 {
-	return SM_VERSION_STRING;
+	return SOURCEMOD_VERSION;
 }
 
 const char *CurlExt::GetExtensionDateString()
 {
-	return SM_BUILD_TIMESTAMP;
+	return SOURCEMOD_BUILD_TIME;
 }