Do not typedef char16_t if it is a keyword.

Don't define char16_t on platforms where char16_t is a keyword, as
C11 and C++11 define it to be.

(cherry picked from commit dfdbe61d28dbf3e45b6108d739170482ca19a03c)
Change-Id: I6717bc2133c1363ecd85861f3869e1eabd2ce96a
1 file changed