disable xinerama and xinput if libraries are missing.

CMakeLists.txt

@@ -799,11 +799,19 @@ if(UNIX AND NOT APPLE)
 		set(PLATFORM_LINKLIBS "${PLATFORM_LINKLIBS} ${X11_X11_LIB}")
 
 		if(WITH_X11_XINPUT)
+			if(X11_Xinput_LIB)
 				set(PLATFORM_LINKLIBS "${PLATFORM_LINKLIBS} ${X11_Xinput_LIB}")
+			else()
+				set(WITH_X11_XINPUT OFF)
+			endif()
 		endif()
 
 		if(WITH_X11_XINERAMA)
+			if(X11_Xinerama_LIB)
 				set(PLATFORM_LINKLIBS "${PLATFORM_LINKLIBS} ${X11_Xinerama_LIB}")
+			else()
+				set(WITH_X11_XINERAMA OFF)
+			endif()
 		endif()
 
 		if(WITH_X11_XF86VMODE)
@@ -2138,6 +2146,7 @@ if(FIRST_RUN)
 	info_cfg_option(WITH_INSTALL_PORTABLE)
 	info_cfg_option(WITH_X11_XF86VMODE)
 	info_cfg_option(WITH_X11_XINPUT)
+	info_cfg_option(WITH_X11_XINERAMA)
 	info_cfg_option(WITH_MEM_JEMALLOC)
 	info_cfg_option(WITH_SYSTEM_GLEW)
 	info_cfg_option(WITH_SYSTEM_OPENJPEG)