When using `ADD' with an immediate operand, the instruction is
actually `ADD Rd, Rn, #<imm12>', that is, the maximum of the
immediate operand cannot exceed 4095. It will fail to compile with
LLVM.
However, in GCC, due to some legacy compatibility considerations,
`ADD.W' will be automatically emitted when the immediate operand is
larger than 4095.
* builds/unix/ftconfig.in, include/freetype/config/ftconfig.h
(FT_MulFix_arm) [__GNUC__]: Support clang compiler.
* src/truetype/ttinterp.c (TT_MulFix14_arm) [__GNUC__]: Ditto.