[regex] Provide a default definition of SIZE_MAX

[Ulrich Drepper]

If you noticed stdint.h isn't included, why didn't you add this to the 
patch as well?  I've done this now and added the default definition.

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➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖