add cmake option WITH_SYSTEM_OPENJPEG so linux can build cycles without having libopenjpeg installed.

CMakeLists.txt

@@ -159,7 +159,7 @@ unset(PLATFORM_DEFAULT)
 if(UNIX AND NOT APPLE)
 	option(WITH_X11_XINPUT "Enable X11 Xinput (tablet support and unicode input)"	ON)
 	option(WITH_X11_XF86VMODE "Enable X11 video mode switching"	ON)
-	option(WITH_SYSTEM_GLEW "Use GLEW OpenGL wrapper library bundled with blender" ON)
+	option(WITH_SYSTEM_GLEW "Use GLEW OpenGL wrapper library provided by the operating system" ON)
 
 	# freebsd doesn't seems to support XDND
 	if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD")
@@ -170,6 +170,17 @@ else()
 	set(WITH_SYSTEM_GLEW OFF)
 endif()
 
+
+# (unix defaults to System OpenJPEG On)
+if(UNIX AND NOT APPLE)
+	set(PLATFORM_DEFAULT ON)
+else()
+	set(PLATFORM_DEFAULT OFF)
+endif()
+option(WITH_SYSTEM_OPENJPEG "Use the operating systems OpenJPEG library" ${PLATFORM_DEFAULT})
+unset(PLATFORM_DEFAULT)
+
+
 # Modifiers
 option(WITH_MOD_FLUID        	"Enable Elbeem Modifier (Fluid Simulation)" ON)
 option(WITH_MOD_SMOKE        	"Enable Smoke Modifier (Smoke Simulation)" ON)
@@ -1485,7 +1496,7 @@ endif()
 
 
 if(WITH_IMAGE_OPENJPEG)
-	if(UNIX AND NOT APPLE)
+	if(WITH_SYSTEM_OPENJPEG)
 		# dealt with above
 	else()
 		set(OPENJPEG_INCLUDE_DIRS "${CMAKE_SOURCE_DIR}/extern/libopenjpeg")
@@ -1791,8 +1802,9 @@ 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_SYSTEM_GLEW)
 	info_cfg_option(WITH_MEM_JEMALLOC)
+	info_cfg_option(WITH_SYSTEM_GLEW)
+	info_cfg_option(WITH_SYSTEM_OPENJPEG)
 
 	info_cfg_text("Image Formats:")
 	info_cfg_option(WITH_IMAGE_CINEON)