Add hurd cmake configuration

debian/patches/hurd.patch

+Index: mariadb-10.1-10.1.35/cmake/os/GNU.cmake
+===================================================================
+--- /dev/null
++++ mariadb-10.1-10.1.35/cmake/os/GNU.cmake
+@@ -0,0 +1,33 @@
++
++# Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
++# 
++# This program is free software; you can redistribute it and/or modify
++# it under the terms of the GNU General Public License as published by
++# the Free Software Foundation; version 2 of the License.
++#
++# This program is distributed in the hope that it will be useful,
++# but WITHOUT ANY WARRANTY; without even the implied warranty of
++# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
++# GNU General Public License for more details.
++#
++# You should have received a copy of the GNU General Public License
++# along with this program; if not, write to the Free Software
++# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA 
++
++# This file includes GNU/Hurd specific options and quirks, related to system checks
++
++INCLUDE(CheckSymbolExists)
++
++# Something that needs to be set on legacy reasons
++SET(_GNU_SOURCE 1)
++SET(CMAKE_REQUIRED_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} -D_GNU_SOURCE=1)
++
++# Ensure we have clean build for shared libraries
++# without unresolved symbols
++# Not supported with AddressSanitizer
++IF(NOT WITH_ASAN)
++  SET(LINK_FLAG_NO_UNDEFINED "-Wl,--no-undefined")
++ENDIF()
++
++# 64 bit file offset support flag
++SET(_FILE_OFFSET_BITS 64)

debian/patches/series

@@ -23,3 +23,4 @@ mytop-merge_src:mytop_improvements.patch
 Add_default_ExecStartPre_to_mariadb@.service.patch
 0024-Revert-to-using-system-pcre-library.patch
 0025-Change-the-default-optimization-from-O3-to-O2-in-mys.patch
+hurd.patch