Re-factors only. Renames the obsolete REG enums in api.ir test to DR_REG. AVX-512 tests need to use the DR_REG names anyway, since we stopped providing REG versions for new AVX-512 registers.
Issue: #1312
Re-factors only. Renames the obsolete REG enums in api.ir test to DR_REG. AVX-512 tests need to use the DR_REG names anyway, since we stopped providing REG versions for new AVX-512 registers.
Issue: #1312