Migrate glyph mask to A8 in case of mixed-format glyphs.

This fixes the remaining image-backend problems with bug 13479:

	Ugly Courier New font with cairo 1.4.12
	https://bugs.freedesktop.org/show_bug.cgi?id=13479

although the xlib-backend had been fixed previously.

Specifically, if an A1 glyph is first encountered, then subsequent
glyphs will still be rendered with antialiasing, (previously they
would be rendered very poorly without antialiasing).

Similarly, if the first glyph encountered has component-alpha
sub-pixel antialiasing and then an A1 or A8 glyph is encountered
then all glyphs will rendered in A8 (grayscale antialiasing).
Previously, the non-subpixel-antialiased glyphs would not appear
at all.

Cherry picked from commit ecb895803b9d2a3fd142f4a2c694ca08c5581f0e

0 files changed, 0 insertions, 0 deletions