Revert "jenkins.sh: disable parallel build"

This reverts commit a352642587d8835deb3c6f55da7986f427835157.

I've confused the libasn1c and asn1c repositories. libasn1c does not
need this workaround, asn1c does.

Related Change-Id: I80eecc60b96e87710218089dfdd1a3f87b40a8b1 (asn1c)
Change-Id: I73eac905524688939e133b6f91ad85514dc0393a
1 file changed