util: split out memcmp()/memset() related calls into memory-util.[ch]

Just some source rearranging.

src/basic/util.c

@@ -51,20 +51,6 @@ int saved_argc = 0;
 char **saved_argv = NULL;
 static int saved_in_initrd = -1;
 
-size_t page_size(void) {
-        static thread_local size_t pgsz = 0;
-        long r;
-
-        if (_likely_(pgsz > 0))
-                return pgsz;
-
-        r = sysconf(_SC_PAGESIZE);
-        assert(r > 0);
-
-        pgsz = (size_t) r;
-        return pgsz;
-}
-
 bool plymouth_running(void) {
         return access("/run/plymouth/pid", F_OK) >= 0;
 }
@@ -165,28 +151,6 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
         return NULL;
 }
 
-bool memeqzero(const void *data, size_t length) {
-        /* Does the buffer consist entirely of NULs?
-         * Copied from https://github.com/systemd/casync/, copied in turn from
-         * https://github.com/rustyrussell/ccan/blob/master/ccan/mem/mem.c#L92,
-         * which is licensed CC-0.
-         */
-
-        const uint8_t *p = data;
-        size_t i;
-
-        /* Check first 16 bytes manually */
-        for (i = 0; i < 16; i++, length--) {
-                if (length == 0)
-                        return true;
-                if (p[i])
-                        return false;
-        }
-
-        /* Now we know first 16 bytes are NUL, memcmp with self.  */
-        return memcmp(data, p + i, length) == 0;
-}
-
 int on_ac_power(void) {
         bool found_offline = false, found_online = false;
         _cleanup_closedir_ DIR *d = NULL;