converted the use of internal 'verbose' level tracing to SAL_INFO/SAL_WARN

Change-Id: Iab89d9b5c75fe476c6516718f1cee3d01d196858
Reviewed-on: https://gerrit.libreoffice.org/17632Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>