loader: g_realloc(p, 0) frees and returns NULL, simplify

Once upon a time, it was decided that qemu_realloc(ptr, 0) should
abort.  Switching to glib retired that bright idea.  A bit of code
that was added to cope with it (commit 3e372cf8) is still around.  Bury
it.

See also commit 6528499f.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

include/hw/elf_ops.h

@@ -147,18 +147,13 @@ static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
         }
         i++;
     }
-    if (nsyms) {
-        syms = g_realloc(syms, nsyms * sizeof(*syms));
+    syms = g_realloc(syms, nsyms * sizeof(*syms));
 
-        qsort(syms, nsyms, sizeof(*syms), glue(symcmp, SZ));
-        for (i = 0; i < nsyms - 1; i++) {
-            if (syms[i].st_size == 0) {
-                syms[i].st_size = syms[i + 1].st_value - syms[i].st_value;
-            }
+    qsort(syms, nsyms, sizeof(*syms), glue(symcmp, SZ));
+    for (i = 0; i < nsyms - 1; i++) {
+        if (syms[i].st_size == 0) {
+            syms[i].st_size = syms[i + 1].st_value - syms[i].st_value;
         }
-    } else {
-        g_free(syms);
-        syms = NULL;
     }
 
     /* String table */