Avoid non-standard BSD types in mono/io-layer/wapi_glob.c

The u_char, u_short and u_int types are non-standard and no system headers
are required to provide them. There are no particular use for them and the
builtin standard types will do just as well.

This change is released under the MIT/X11 license.
Print pid_t's portably in mono/metadata/attach.c

The pid_t type is required by POSIX to be a signed integer type (and that it
isn't wider than long in at least one programming environment). Mono has a
bunch of issues with 64-bit pids at the present, this is a start. Cast the
pid to the largest available signed type before printing it.

This change is released under the MIT/X11 license.