Avoid indexed getToken for single call

Change-Id: I3e8e413d2a1e7a0b95e972246d86182156118488
Reviewed-on: https://gerrit.libreoffice.org/65674
Tested-by: Jenkins
Reviewed-by: Matteo Casalin <matteo.casalin@yahoo.com>

cui/source/dialogs/about.cxx

@@ -258,8 +258,7 @@ OUString AboutDialog::GetBuildId()
 
     if (!sBuildId.isEmpty())
     {
-        sal_Int32 nIndex = 0;
-        return sBuildId.getToken( 0, '-', nIndex );
+        return sBuildId.getToken( 0, '-' );
     }
 
     OSL_ENSURE( !sBuildId.isEmpty(), "No BUILDID in bootstrap file" );