Currently, all instructions taking s16imm operands support symbolic
operands. However, for u16imm operands, we only support actual
immediate integers. This causes the assembler to reject code like
ori %r5, %r5, symbol@l
This patch changes the u16imm operand definition to likewise
accept symbolic operands. In fact, s16imm and u16imm can
share the same encoding routine, now renamed to getImm16Encoding.
llvm-svn: 184944