Adds OpenGL/GLEW checks to scons.

Taken mostly verbatim from 3e2eba2

SConstruct

@@ -413,14 +413,6 @@ if env["prereqs"]:
         if env["history"]:
             client_env.Append(CPPDEFINES = ["HAVE_HISTORY"])
 
-        if env["PLATFORM"] == 'darwin':
-            client_env.Append(FRAMEWORKS = "OpenGL")
-            client_env.AppendUnique(LIBS = ["GLEW"])
-        elif env["PLATFORM"] == 'posix':
-            opengl_config = check_output(["pkg-config", "--libs", "--cflags", "gl", "glew"])
-            opengl_flags = client_env.ParseFlags(opengl_config)
-            client_env.MergeFlags(opengl_flags)
-
     if env["forum_user_handler"]:
         mysql_config = check_output(["mysql_config", "--libs", "--cflags"]).replace("\n", " ").replace("-DNDEBUG", "")
         mysql_flags = env.ParseFlags(mysql_config)