Patch for config options (#93)

This config options could be moved to extension. But if we want to
access some config options via numba.config then Numba should provide
extension point for this.

Author: PokhodenkoSA

numba/core/config.py

@@ -222,12 +222,6 @@ def optional_str(x):
         DUMP_SSA = _readenv("NUMBA_DUMP_SSA", int,
                             DEBUG_FRONTEND or DEBUG_TYPEINFER)
 
-        # Save intermediate files being generated by DPPL
-        SAVE_DPPL_IR_FILES = _readenv("NUMBA_SAVE_DPPL_IR_FILES", int, 0)
-
-        # Turn SPIRV-VALIDATION ON/OFF switch
-        SPIRV_VAL = _readenv("NUMBA_SPIRV_VAL", int, 0)
-
         # print debug info of analysis and optimization on array operations
         DEBUG_ARRAY_OPT = _readenv("NUMBA_DEBUG_ARRAY_OPT", int, 0)