Deprecate Android-specific SkPaint functions.

The following functions were problematic:
 const SkGlyph& getUnicharMetrics(SkUnichar, const SkMatrix*);
 const SkGlyph& getGlyphMetrics(uint16_t, const SkMatrix*);
 const void* findImage(const SkGlyph&, const SkMatrix*);

Replacing them with calls through SkGlyphCache solved a nasty crash
bug, so they have all been deprecated.

Bug: 11968757
Change-Id: Id746315d41aec5b211b78b172a883c2061130f08