printf.m4: fix a bug in detecting printf %j support * m4/printf.m4 (gl_PRINTF_SIZES_C99): Fail any system for which uintmax_t is defined in neither stdint.h nor inttypes.h. Before, this macro might have mistakenly set gl_cv_func_printf_sizes_c99=yes on such a system. Spotted by Zev Weiss.