Fix error of parser:
> error get info about worker process status 3150292: strconv.ParseInt:
> parsing "4294967293": value out of range
$ grep Groups /proc/self/status
Groups: 20001 [...] 4294967293
Removes need for redundant ParentWithContext implementations. It had led
to it being unsupported on FreeBSD and OpenBSD even though
PpidWithContext was available for them, and different implementations
for getting the parent info used in ParentWithContext and
PpidWithContext on Darwin and Linux.
Add support (for Linux and Windows for now) for reading the
environment variables of a process, with a similar syntax to
os.Environ().
For Windows, this includes some refactoring for clean access to the
RTL_USER_PROCESS_PARAMETERS structure which points to the command
line and the environment variables.
* All context-less wrapping functions (the ones without WithContext
suffix) were moved into process.go since they all are the same.
* Call context is now passed to all underlying functions in
*WithContext() functions.
* All common *BSD bits were moved to process_bsd.go.
* Process.Tgid() method lacked a WithContext counterpart, so
Process.TgidWithContext() was added for uniformity.
* NewProcessWithContext() function was added since NewProcess() is
used a lot throughout the module, and there is no way to pass a
context to it.
This is a part of #761 effort.
This enables using gopsutil in a codebase that gets built on other OSes
than the ones supported. Instead of a build failure as before, due to
the build tags, gopsutil will now throw an "not implemented" runtime
error.
Fixes#234.
