Caller of ImpSvNumberformatScan::GetKeyWord() needs to know if
English or locale's keyword was found and act on it.

Pointed out by an assert when attempting to copy "STANDARD" length
characters (8) from "General" (7), which doesn't harm because when
not in debug it copied the terminating 0-character. However, the
keyword name also needs to be replaced for the locale's resulting
format code.

Change-Id: Ia5211b307ea44c1ba9c2b86786368355c570d4a2
Reviewed-on: https://gerrit.libreoffice.org/55293Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>