Store global cpp option.

Cython/Compiler/CmdLine.py

@@ -89,7 +89,7 @@ def parse_command_line(args):
                 options.c_only = 0
                 options.obj_only = 0
             elif option in ("-+", "--cplus"):
-                options.cplus = 1
+                Options.cplus = options.cplus = 1
             elif option == "--embed":
                 Options.embed = True
             elif option.startswith("-I"):

Cython/Compiler/Options.py

@@ -6,6 +6,7 @@ cache_builtins = 1  #  Perform lookups on builtin names only once
 
 embed_pos_in_docstring = 0
 gcc_branch_hints = 1
+cplus = 0
 
 pre_import = None
 docstrings = True