proc_service.h as an installed header

[Florian Weimer]

glibc has received a request to turn proc_service.h into an installed 
header:

   https://sourceware.org/bugzilla/show_bug.cgi?id=20311

The request seems reasonable.

The only question is who owns this API.  glibc is just a consumer here, 
and the traditional provider is GDB, so I GDB would be the natural

The API definitions seem to have drifted a bit, e.g.:

--- glibc/git/nptl_db/proc_service.h
+++ binutils-gdb/gdb/gdb_proc_service.h
…
-extern ps_err_e ps_pstop (const struct ps_prochandle *);
-extern ps_err_e ps_pcontinue (const struct ps_prochandle *);
+extern ps_err_e ps_pstop (struct ps_prochandle *);
+extern ps_err_e ps_pcontinue (struct ps_prochandle *);

Perhaps we should clean this up before making this a more public API?

Thanks,
Florian