Method parseSetAssignment treats every operand with '$' sign as register and the...

Method parseSetAssignment treats every operand with '$' sign as register and the parsing is directed to set alias for register. This will result in errors reported when expressions containing label references are parsed(for example long jumps)
As we can't make a complete solution now it has been decided to enable .set directive to handle long jump expressions. This will cause parser to report errors when parsing integer based register assignments, for example:
   .set r3, will be reported as error. Still, the need for expressions is higher priority as the integer based register assignments are Mips specific and can be avoided using register names.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196773 91177308-0d34-0410-b5e6-96231b3b80d8