* sysdep.c [GNU_LINUX]: Fix fd and memory leaks and similar issues.

* sysdep.c [GNU_LINUX]: Fix fd and memory leaks and similar issues.

(procfs_ttyname): Don't use uninitialized storage if emacs_fopen
or fscanf fails.
(system_process_attributes): Prefer plain char to unsigned char
when either will do.  Clean up properly if interrupted or if
memory allocations fail.  Don't assume sscanf succeeds.  Remove
no-longer-needed workaround to stop GCC from whining.  Read
command-line once, instead of multiple times.  Check read status a
bit more carefully.