vmcoreinfo: add kallsyms_num_syms symbol

The rest of the kallsyms symbols are useless without knowing the number of
symbols in the table.  In an earlier patch, I somehow dropped the
kallsyms_num_syms symbol, so add it back in.

Link: https://lkml.kernel.org/r/20220808205410.18590-1-stephen.s.brennan@oracle.com
Fixes: 5fd8fea ("vmcoreinfo: include kallsyms symbols")
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: brenns10

kernel/crash_core.c

@@ -494,6 +494,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 
 #ifdef CONFIG_KALLSYMS
 	VMCOREINFO_SYMBOL(kallsyms_names);
+	VMCOREINFO_SYMBOL(kallsyms_num_syms);
 	VMCOREINFO_SYMBOL(kallsyms_token_table);
 	VMCOREINFO_SYMBOL(kallsyms_token_index);
 #ifdef CONFIG_KALLSYMS_BASE_RELATIVE