highlight errors and warnings with correct face

git-svn-id: https://svn.r-project.org/ESS/trunk@5736 0bbaf3bd-34e0-0310-bf65-c717079852d4
tracebug: don't allow compilation to mess up our faces

git-svn-id: https://svn.r-project.org/ESS/trunk@5737 0bbaf3bd-34e0-0310-bf65-c717079852d4