Move zoom functions into x.c

This makes x(un)loadfonts internal to x.c.  Needed to reorder includes
and move a typedef to keep the compiler happy.

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

st.h

@@ -100,6 +100,7 @@ typedef struct {
 } Glyph;
 
 typedef Glyph *Line;
+typedef XftGlyphFontSpec GlyphFontSpec;
 
 typedef struct {
 	Glyph attr; /* current char attributes */