Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: r257315, r260445, r264803

Update byacc to 20140422

Update to byacc 20140409
Among all the modifications, this new byacc also solves a 14 year old bug [1]

PR: bin/23254 [1]
Submitted by: marka@nominum.com [1]
MFC after: 3 weeks

Import byacc 20140409