...so no need to do that again in the body of the BPixelRaster ctor (which had
needlessly been done ever since the code's introduction with
6f769fb8 "INTEGRATION: CWS aw033").  And
BPixelRaster::reset appears to have otherwise been unused, so can be removed.

Change-Id: Icd8e09bfe225be2c6695d8a137c271dca5a70de7
Reviewed-on: https://gerrit.libreoffice.org/48184Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>