Fix build for pre-C99 compilers without INT32_MIN
Fix build for pre-C99 compilers without INT32_MIN

Fix a regression introduced by bb9db98.

kealist/ren-c,draegtun/ren-c,hostilefork/rebol,rgchris/ren-c,codebybrett/ren-c,codebybrett/ren-c,rgchris/ren-c,rgchris/ren-c,codebybrett/ren-c,codebybrett/ren-c,draegtun/ren-c,kealist/ren-c,kealist/ren-c,kealist/ren-c,giuliolunati/ren-c,codebybrett/ren-c,codebybrett/ren-c,hostilefork/rebol,kealist/ren-c,draegtun/ren-c,draegtun/ren-c,hostilefork/rebol,hostilefork/rebol,rgchris/ren-c,draegtun/ren-c,hostilefork/rebol,giuliolunati/ren-c,hostilefork/rebol,rgchris/ren-c,giuliolunati/ren-c,kealist/ren-c,giuliolunati/ren-c,giuliolunati/ren-c,draegtun/ren-c