Static declaration of 'sallocx' follows non-static declaration on FreeBSD 13.1

main fails to build on FreeBSD 13.1-RELEASE-p2 when --without-jemalloc is present:

In file included from mem.c:58:
./jemalloc_shim.h:70:1: error: static declaration of 'sallocx' follows non-static declaration
sallocx(void *ptr, int flags) {
^
/usr/include/malloc_np.h:99:8: note: previous declaration is here
size_t  sallocx(const void *ptr, int flags);
        ^
1 error generated.