uchar-h: Support multiple gnulib-tool invocations in the same package.

uchar-h: Support multiple gnulib-tool invocations in the same package.

* lib/uchar.in.h (GNULIB_defined_btoc32, GNULIB_defined_c32isalnum,
GNULIB_defined_c32isalpha, GNULIB_defined_c32isblank,
GNULIB_defined_c32iscntrl, GNULIB_defined_c32isdigit,
GNULIB_defined_c32isgraph, GNULIB_defined_c32islower,
GNULIB_defined_c32isprint, GNULIB_defined_c32ispunct,
GNULIB_defined_c32isspace, GNULIB_defined_c32isupper,
GNULIB_defined_c32isxdigit, GNULIB_defined_c32tolower,
GNULIB_defined_c32toupper, GNULIB_defined_c32width,
GNULIB_defined_c32snrtombs, GNULIB_defined_c32srtombs,
GNULIB_defined_c32stombs, GNULIB_defined_c32swidth,
GNULIB_defined_c32tob, GNULIB_defined_mbsnrtoc32s,
GNULIB_defined_mbsrtoc32s, GNULIB_defined_mbstoc32s,
GNULIB_defined_c32_get_type_test, GNULIB_defined_c32_apply_type_test,
GNULIB_defined_c32_get_mapping, GNULIB_defined_c32_apply_mapping): New
macros.