Fix support of scripts in w32font.c (Bug#19993)

Fix support of scripts in w32font.c  (Bug#19993)

 src/w32font.c (font_supported_scripts): Add subranges for Latin
 Supplement, Latin Extended-A/B, Vai, Supplemental Punctuation, Tai
 Le, Buginese, Yijing Hexagrams, Ancient Greek Numbers, Tai Xuan
 Jing, Counting Rods, Sundanese, Lepcha, Ol Chiki, Saurashtra,
 Kayah Li, Rejang, Ancient Symbols, Phistos Disc, Carian, Lycian,
 Lydian, Dominoe Tiles, and Mahjong Tiles.  Break the Mathematical
 Alphanumeric Symbols into several "scripts" like fontset.el does.
 (syms_of_w32font): DEFSYM all the new script symbols.

 lisp/international/fontset.el (script-representative-chars): Add a
 representative character for 'vai'.