Replace errdetail("%s", ...) with errdetail_internal("%s", ...).

There may be some other places where we should use errdetail_internal,
but they'll have to be evaluated case-by-case.  This commit just hits
a bunch of places where invoking gettext is obviously a waste of cycles.

src/backend/utils/fmgr/dfmgr.c

@@ -378,7 +378,7 @@ incompatible_module_error(const char *libname,
 	ereport(ERROR,
 			(errmsg("incompatible library \"%s\": magic block mismatch",
 					libname),
-			 errdetail("%s", details.data)));
+			 errdetail_internal("%s", details.data)));
 }
 
 /*