ext: disable PLY debugging
ext: disable PLY debugging

Very rarely does anyone ever mess with PLY code, and when
such a need arises, the developer can reenable this flag in
their working tree.

This will eliminate the "generating LALR tables" message
during compilation and temporary parser.out file as well.
(transplanted from a0d94ac7e004c0e831549883fd247dbce577879f)

LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5