getchar macro/decl conflict

[Benjamin Kosnik]

> +  Looks like we need to #undef getchar, somewhere.

Yeah. The procedure:

-) add undefs in the file, as we did here:
libstdc++-v3/include/c/bits/std_cwctype

-) add any os-specific macros to force the non-macro def in the os's .h file
(see c/bits/include/std_cstring.h and config/os/gnu-linux/bits/os_defines)

> +  Can the diag be updated to check if the number of arguments is 1, and
>    if so, print "argument" instead of "arguments"?

haha. I'm in favor of kung-fu diagnostic messages, myself.

-benjamin