strtoimax, strtoumax: port to HP-UX 11.11

strtoimax, strtoumax: port to HP-UX 11.11

Problem reported by Daniel Richard G. in
<http://lists.gnu.org/archive/html/bug-gnulib/2013-10/msg00023.html>.
* lib/inttypes.in.h (strtoumax): Replace strtoumax if
REPLACE_STRTOUMAX, thus treating it consistently with strtoimax.
* m4/inttypes.m4 (gl_INTTYPES_H_DEFAULTS): Add default for
REPLACE_STRTOUMAX.
* m4/strtoimax.m4 (gl_FUNC_STRTOIMAX):
* m4/strtoumax.m4 (gl_FUNC_STRTOUMAX):
Replace the function if defined as a macro but not as a function.
* modules/inttypes-incomplete (inttypes.h): Substitute
REPLACE_STRTOUMAX.
* modules/strtoumax (configure.ac): Replace strtoumax if
REPLACE_STRTOUMAX.