$OpenBSD: patch-Source_kwsys_CMakeLists_txt,v 1.5 2018/06/14 17:04:45 sthen Exp $

patch to disable libexecinfo / execinfo.h; seems it can be picked up
on ports-gcc arches.

Index: Source/kwsys/CMakeLists.txt
--- Source/kwsys/CMakeLists.txt.orig
+++ Source/kwsys/CMakeLists.txt
@@ -558,7 +558,7 @@ IF(KWSYS_USE_SystemInformation)
     SET_PROPERTY(SOURCE SystemInformation.cxx APPEND PROPERTY
       COMPILE_DEFINITIONS KWSYS_CXX_HAS__ATOI64=1)
   ENDIF()
-  IF(UNIX)
+  IF(UNIX AND NOT (CMAKE_SYSTEM MATCHES "OpenBSD"))
     INCLUDE(CheckIncludeFileCXX)
     # check for simple stack trace
     # usually it's in libc but on FreeBSD
