CMake: Hide pledge() support behind an OpenBSD check

CMakeLists.txt

@@ -31,7 +31,9 @@ if(NOT LIBMGBA_ONLY)
 		set(USE_EDITLINE ON CACHE BOOL "Whether or not to enable the CLI-mode debugger")
 	endif()
 	set(USE_GDB_STUB ON CACHE BOOL "Whether or not to enable the GDB stub ARM debugger")
-	set(USE_PLEDGE OFF CACHE BOOL "Whether or not to drop privileges with pledge")
+	if (CMAKE_SYSTEM_NAME STREQUAL OpenBSD)
+		set(USE_PLEDGE ON CACHE BOOL "Whether or not to drop privileges with pledge")
+	endif()
 	set(USE_FFMPEG ON CACHE BOOL "Whether or not to enable FFmpeg support")
 	set(USE_ZLIB ON CACHE BOOL "Whether or not to enable zlib support")
 	set(USE_MINIZIP ON CACHE BOOL "Whether or not to enable external minizip support")
@@ -1230,7 +1232,9 @@ if(NOT QUIET AND NOT LIBMGBA_ONLY)
 		message(STATUS "	CLI debugger: ${USE_EDITLINE}")
 	endif()
 	message(STATUS "	GDB stub: ${USE_GDB_STUB}")
-	message(STATUS "	pledge: ${USE_PLEDGE}")
+	if(CMAKE_SYSTEM_NAME STREQUAL OpenBSD)
+		message(STATUS "	pledge: ${USE_PLEDGE}")
+	endif()
 	message(STATUS "	GIF/Video recording: ${USE_FFMPEG}")
 	message(STATUS "	Screenshot/advanced savestate support: ${USE_PNG}")
 	message(STATUS "	ZIP support: ${SUMMARY_ZIP}")