FDPIC: Fix memory leak

The shdr4extnum variable isn't being freed in the cleanup process of
elf_fdpic_core_dump().

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf_fdpic.c

@@ -1864,6 +1864,7 @@ cleanup:
 	kfree(psinfo);
 	kfree(notes);
 	kfree(fpu);
+	kfree(shdr4extnum);
 #ifdef ELF_CORE_COPY_XFPREGS
 	kfree(xfpu);
 #endif