Support for scaleX and skewX in Minikin

Passes textScaleX and textSkewX parameters, as well as paint flags from
the paint to Minikin, to support nontrivial scale and stretch of text.
Passing paint flags should minimize kerning artifacts arising from
mismatch of glyph rendering in layout and drawing.

Also, replaces unsafe snprintf to a fixed size buffer with a safe
version, which still avoids an allocation per layout operation.

This is part of the fix for bug 15186705 "Usability of the suggestion
strip in recent OTA's is severely reduced"

Change-Id: I79788383135836f4c21fb84405f36382627bf959