For legacy reasons, we kept around the use of UTF-16 internally
in AAPT2. We don't need this and this CL removes all instances of
std::u16string and StringPiece16. The only places still needed
are when interacting with the ResTable APIs that only operate in
UTF16.
Change-Id: I492475b84bb9014fa13bf992cff447ee7a5fe588
Mingw32 4.8 is kind of picky with macros and some complicated template
stuff. Luckily there was another way to represent the
SFINAE code that works on all platforms. Yay!
Change-Id: Idc2e38f47bfdc57b394550bfa0f53cc0b825df25