var: Fix unexporting of local variables using unset

Local variables and other variables with the flag VSTRFIXED set
could not be unexported using the unset command.  Fix this by
adding a special case in setvareq for them.

Reported-by: Christoph Anton Mitterer <calestyo@scientia.org>
Fixes: e3c9a7dd7097 ("[VAR] Move unsetvar functionality into setvareq")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
1 file changed