cppfiles.c (lookup_include_file): Rename to open_file.
* cppfiles.c (lookup_include_file): Rename to open_file.
Always create a splay tree value, even on syscall failures.
Negative entries indicated by fd == -2.
Re-open files closed in the meantime.
(_cpp_fake_include): Create a negative splay tree entry.
(find_include_file, cpp_read_file): Update for function name
change.
* gcc.gd/cpp/mi4.c: Testcase.