Towards support of taskset(1) within util-linux package

[Mark Geisert <mark at maxrnd dot com>]

Hi Yaakov,
I patched util-linux locally to build the 'taskset' tool so I could test 
my implementation of the get- and set-affinity functions within Cygwin. 
The implementation will be part of the upcoming Cygwin 3.1.0 release.

I'm not sure how to manipulate the build environment so I could supply a 
'git send-mail' of a 'git format-patch' that would be usable to you.
I hope the following 'diff -u' outputs will be useful; but if you'd prefer 
a different format just let me know.

Thank you for all your work on Cygwin!

..mark

cd /usr/src/util-linux-2.33.1-1.src
diff -u util-linux.cygport.safe util-linux.cygport
--- util-linux.cygport.safe     2019-03-05 12:07:51.000000000 -0800
+++ util-linux.cygport  2019-05-23 22:43:40.520885600 -0700
@@ -147,7 +147,6 @@
   --enable-more
   --enable-pg
   --disable-setterm
-  --disable-schedutils
   --disable-wall
   --disable-write
   --disable-use-tty-group

cd util-linux-2.33.1-1.x86_64/src/util-linux-2.33.1/lib 
diff -u cpuset.c.safe cpuset.c
--- cpuset.c.safe       2018-06-04 00:57:02.792445800 -0700
+++ cpuset.c    2019-06-21 01:36:44.078702800 -0700
@@ -60,7 +60,7 @@
  */
 int get_max_number_of_cpus(void)
 {
-#ifdef SYS_sched_getaffinity
+#if defined(SYS_sched_getaffinity) || defined(__CYGWIN__)
        int n, cpus = 2048;
        size_t setsize;
        cpu_set_t *set = cpuset_alloc(cpus, &setsize, NULL);
@@ -71,8 +71,12 @@
        for (;;) {
                CPU_ZERO_S(setsize, set);

+#if defined(__CYGWIN__)
+               n = sched_getaffinity(0, setsize, set);
+#else
                /* the library version does not return size of cpumask_t */
                n = syscall(SYS_sched_getaffinity, 0, setsize, set);
+#endif

                if (n < 0 && errno == EINVAL && cpus < 1024 * 1024) {
                        cpuset_free(set);