Allow multiple styles for fallback fonts

Fallback fonts are now recorded with their styles in the list of
available fonts (which is now a doubly-linked list). NextLogicalFont()
has a new parameter, providing the originally requested fontID, from
which we can determine the requested style, which we then pass to
find_best_face() to pick from the available styles.

Bug: 4390209
Change-Id: I0c45fd7cefd00df3805bd75df77c519f6d922fe7
1 file changed