small patch for numactl. Comments?

[Larry McVoy]

Hi folks, some CDN people are dragging me out of retirement to work
on FreeBSD.  Which I have to say is sort of fun since I started my
kernel hacking on SunOS 4.x which was a very very nice version of 
BSD.  But FreeBSD has mostly caught up, so it's pleasant.

I'm wacking LMbench to be numa aware and this patch would help me make
sure that when you are a numa machine you could insist that people 
run the benchmark via numactl (imma gonna blog about numa, it sucks
unless you are numa aware).

I did some docs but I'm new to the FreeBSD man macros, would love 
feedback on how to do that right.

--- numactl.1	2017-11-13 17:51:26.243473000 -0800
+++ numactl.1.lm	2017-11-13 17:51:20.494596000 -0800
@@ -107,6 +107,15 @@
 .El
 .Sh EXIT STATUS
 .Ex -std
+.Sh ENVIRONMENT
+.Nm
+sets the environment variable
+\fINUMACTL=YES\fP
+before running 
+.Ar cmd ...
+so that programs that know that they need to be run under 
+.Nm
+can check.
 .Sh EXAMPLES
 Create a
 .Pa /bin/sh
--- numactl.c	2017-11-13 16:18:36.134359000 -0800
+++ numactl.c.lm	2017-11-13 16:18:28.530953000 -0800
@@ -231,6 +231,7 @@
 			(void) set_numa_domain_cpuaffinity(cpu_domain,
 			    CPU_WHICH_PID, -1);
 
+		putenv("NUMACTL=YES");
 		errno = 0;
 		execvp(*argv, argv);
 		err(errno == ENOENT ? 127 : 126, "%s", *argv);