Sanity checks for shadow glyphs

Partially fixes text, huds and videos in Jeanne d'Arc.
These changes shouldn't negatively impact other games since all it does is makes sure shadow glyphs are within the vector sizes.
The text, huds and videos still don't fully display, but that's because of something else.
Update PGF.cpp
Update PGF.cpp
Merge pull request #3103 from CPkmn/patch-1

Sanity checks for shadow glyphs