regex: Fix match flags not to include MULTILINE
regex: Fix match flags not to include MULTILINE

G_REGEX_MULTILINE is a compile flag, and thus must be handled
by the caller, not vte.

thestinger/vte-ng,thestinger/vte-ng,saitoha/vte-sixel,thestinger/vte-ng,saitoha/vte-sixel,saitoha/vte-sixel