bitbake.conf: Add seq to HOSTTOOLS
This fixes detecting available signals when configuring perl.
(cnf/configure_sigs.sh)
Without this, running aclocal prints warnings about missing signals,
which can be further demonstraded by running
perl -le 'print for keys %SIG'
Signed-off-by: Jacob Kroon <jacob.kroon@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>