Configure: sched_setaffinity() test moved to auto/unix.

The sched_setaffinity() function was introduced in DragonFly BSD 4.7,
so it is no longer Linux-specific.

Prodded by Sepherosa Ziehau.
diff --git a/auto/os/linux b/auto/os/linux
index fae8842..a0c8795 100644
--- a/auto/os/linux
+++ b/auto/os/linux
@@ -157,20 +157,6 @@
 . auto/feature
 
 
-# sched_setaffinity()
-
-ngx_feature="sched_setaffinity()"
-ngx_feature_name="NGX_HAVE_SCHED_SETAFFINITY"
-ngx_feature_run=no
-ngx_feature_incs="#include <sched.h>"
-ngx_feature_path=
-ngx_feature_libs=
-ngx_feature_test="cpu_set_t mask;
-                  CPU_ZERO(&mask);
-                  sched_setaffinity(0, sizeof(cpu_set_t), &mask)"
-. auto/feature
-
-
 # crypt_r()
 
 ngx_feature="crypt_r()"
diff --git a/auto/unix b/auto/unix
index 52060fc..7c6a855 100644
--- a/auto/unix
+++ b/auto/unix
@@ -300,6 +300,18 @@
 fi
 
 
+ngx_feature="sched_setaffinity()"
+ngx_feature_name="NGX_HAVE_SCHED_SETAFFINITY"
+ngx_feature_run=no
+ngx_feature_incs="#include <sched.h>"
+ngx_feature_path=
+ngx_feature_libs=
+ngx_feature_test="cpu_set_t mask;
+                  CPU_ZERO(&mask);
+                  sched_setaffinity(0, sizeof(cpu_set_t), &mask)"
+. auto/feature
+
+
 ngx_feature="SO_SETFIB"
 ngx_feature_name="NGX_HAVE_SETFIB"
 ngx_feature_run=no