sd-daemon: remove unnecessary memset calls

There is no point in clearing the bits of a "struct stat" when the very
next statement just calls stat or fstat to fill in that same memory.

[zj: two more places]

src/core/load-fragment.c

@@ -2287,7 +2287,6 @@ static int load_from_path(Unit *u, const char *path) {
                 goto finish;
         }
 
-        zero(st);
         if (fstat(fileno(f), &st) < 0) {
                 r = -errno;
                 goto finish;

src/core/service.c

@@ -564,7 +564,6 @@ static int service_load_sysv_path(Service *s, const char *path) {
                 goto finish;
         }
 
-        zero(st);
         if (fstat(fileno(f), &st) < 0) {
                 r = -errno;
                 goto finish;