all: check stdout and stderr status at exit

If stream status is not checked at the end of execution below problem
would not report error, or non-zero exit code.  The uptime is just an
example same was true with all commands of the project.

$ uptime >&- ; echo $?
uptime: write error: Bad file descriptor
1
$ uptime >/dev/full ; echo $?
uptime: write error: No space left on device
1

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

ps/Makefile.am

@@ -21,7 +21,8 @@ pscommand_SOURCES =  \
 	parser.c \
 	select.c \
 	sortformat.c \
-	stacktrace.c
+	stacktrace.c \
+	$(top_srcdir)/lib/fileutils.c
 
 EXTRA_DIST = \
 	HACKING \