shared/microhttp-util: silence gcc warning
../src/journal-remote/microhttpd-util.c: In function ‘check_permissions’:
../src/journal-remote/microhttpd-util.c:301:5: error: function might be candidate for attribute ‘noreturn’ [-Werror=suggest-attribute=noreturn]
301 | int check_permissions(struct MHD_Connection *connection, int *code, char **hostname) {
| ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Fixes #23630.
(cherry picked from commit b547241728487c0dca22780241b04964f2eb37af)