test for #19046 (#19839)

* test for #19046

* add threads flag

tests/misc/t19046.nim

@@ -0,0 +1,19 @@
+discard """
+  targets: "c cpp"
+  matrix: "--threads:on"
+  disabled: "win"
+  disabled: "osx"
+  action: compile
+"""
+
+# bug #19046
+
+import std/os
+
+var t: Thread[void]
+
+proc test = discard
+proc main = 
+  createThread(t, test)
+  pinToCpu(t, 1)
+main()