From FreeBSD
include same flags for OpenBSD

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -22,7 +22,7 @@ INCLUDE (FindPkgConfig)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
+if(${CMAKE_SYSTEM_NAME} MATCHES "Linux" OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
 	set(DEFAULT_EGL ON)
 	set(DEFAULT_GLX ON)
 	set(DEFAULT_WGL OFF)
@@ -230,12 +230,16 @@ if(PIGLIT_BUILD_WGL_TESTS)
 	add_definitions(-DPIGLIT_HAS_WGL)
 endif()
 
-IF(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
+IF(${CMAKE_SYSTEM_NAME} MATCHES "Linux" OR ${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
 	pkg_check_modules(LIBDRM QUIET libdrm)
 	pkg_check_modules(XCB QUIET xcb)
 	pkg_check_modules(XCB_DRI2 QUIET xcb-dri2)
 	pkg_check_modules(GLPROTO QUIET glproto)
 	pkg_check_modules(LIBVULKAN QUIET vulkan)
+
+	if (LIBVULKAN_FOUND)
+		include_directories(${LIBVULKAN_INCLUDE_DIRS})
+	endif()
 ENDIF()
 
 if(LIBDRM_FOUND)
@@ -301,8 +305,8 @@ if (NOT MSVC)
 		SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse2 -mfpmath=sse")
 	else()
 		# degrade performance a bit, but enforce required precision
-		SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffloat-store")
-		SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffloat-store")
+		# SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffloat-store")
+		# SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffloat-store")
 	endif()
 	CHECK_C_COMPILER_FLAG("-Wall" C_COMPILER_FLAG_WALL)
 	IF (C_COMPILER_FLAG_WALL)
@@ -429,7 +433,7 @@ endif()
 
 check_c_source_compiles(
 	"
-	#define _POSIX_C_SOURCE 199309L
+	#define _POSIX_C_SOURCE 200112L
 	#include <time.h>
 	int main() { return clock_gettime(CLOCK_MONOTONIC, NULL); }
 	"
