Auto merge of #1206 - semarie:mincore, r=gnzlbg

mincore has been removed from upcoming OpenBSD 6.5

remove test from CI on OpenBSD for "mincore" function.

it has been removed from upcoming 6.5:
- https://marc.info/?l=openbsd-cvs&m=154723400730318
- openbsd/src@54e4f6b

I am only removing the test from CI, not touching exported function from Rust libc to avoid a breaking change.

libc-test/build.rs

@@ -857,6 +857,10 @@ fn main() {
             // to be removed now
             "system" | "ptrace" if ios => true,
 
+            // Removed in OpenBSD 6.5
+            // https://marc.info/?l=openbsd-cvs&m=154723400730318
+            "mincore" if openbsd => true,
+
             _ => false,
         }
     });