Fix comment typos in OutputDevice::DrawTransparent()

Change-Id: I52e9d505719b3f3b985cd5300ebacb5caa57873f
Reviewed-on: https://gerrit.libreoffice.org/8777
Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>
Fix another typo in a comment

Change-Id: Ic998270701d2e8d2b562ccc869bca0a8d0aac728
Reviewed-on: https://gerrit.libreoffice.org/8778
Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>