[m4] Reverted isxxx() casts applied in r21597.  Thanks to chromatic++ for pointing out the issues with the commit.
[m4] Reverted isxxx() casts applied in r21597.  Thanks to chromatic++ for
pointing out the issues with the commit.


git-svn-id: 25691d43496b77c53f0b494379003863a981bfc4@21617 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

bschmalhofer/m4