Merge r1535027, 1535157, and 1541486 from trunk:

PR: 55690

r1535027:

configure.in: Fix Linux kernel version detection, which did not
anticipate "3.11.x"-style double digit versioning.

Submitted by: jorton

r1535157:

configure.in: Fix r1535027 for Linux kernel versions x.0.y.

Submitted by: jorton

r1541486:

Fix sed re escaping issue in recognition of Linux kernel version.

Submitted by: Arfrever Frehtes Taifersar Arahesis <arfrever.fta gmail.com>
Reviewed by: trawick



git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.5.x@1541489 13f79535-47bb-0310-9956-ffa450edef68