Change prange loop conversion approach to retain the header block and put the parfor there followed by a jump to the original exit block.  No other block branches need to be modified.
Change prange loop conversion approach to retain the header block and put the parfor there followed by a jump to the original exit block.  No other block branches need to be modified.

stuartarchibald/numba,numba/numba,cpcloud/numba,stuartarchibald/numba,IntelLabs/numba,stuartarchibald/numba,numba/numba,IntelLabs/numba,cpcloud/numba,numba/numba,seibert/numba,seibert/numba,seibert/numba,IntelLabs/numba,IntelLabs/numba,seibert/numba,stuartarchibald/numba,numba/numba,cpcloud/numba,numba/numba,cpcloud/numba,IntelLabs/numba,stuartarchibald/numba,cpcloud/numba,seibert/numba