In some cases bash fails to build parallel make jobs. Provide a patch.

[1] https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=4c2ebbf4b8bc660beb98cc2d845c73375d6e4f50

PR: 251755
Reported by: mikael, freebsd@bengrimm.net, jakob@grimstveit.no
Submitted by: rcarter@pinyon.org
Obtained from: gentoo [1]