buildroot

openssl: re-enable parallel build

The previous incarnation was incomplete, it only applied one of the
Gentoo patches, hence it had corner cases.
Apply all 4 patches as pointed out by Mike on the mailing list.

Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>