gresources: fix memory leak from libelf

Memory was leaking when allocating it inside libelf and losing the pointer to it (it was an automatic variable) when returning NULL from the get_elf function in some cases

Closes #3242

Signed-off-by: Maxim Moskalets <Maxim.Moskalets@kaspersky.com>

gio/gresource-tool.c

@@ -165,6 +165,7 @@ get_elf (const gchar *file,
 
   if (elf_kind (elf) != ELF_K_ELF)
     {
+      elf_end (elf);
       g_close (*fd, NULL);
       *fd = -1;
       return NULL;