box2d: update windows libs to 3.1.0 and call thread.yield in vendor/libc

vendor/libc/sched.odin

@@ -1,6 +1,7 @@
 package odin_libc
 
 import "core:time"
+import "core:thread"
 
 Clock :: enum i32 {
 	Monotonic = 1,
@@ -26,5 +27,9 @@ clock_gettine :: proc "c" (clockid: Clock, tp: ^Time_Spec) -> i32 {
 
 @(require, linkage="strong", link_name="sched_yield")
 sched_yield :: proc "c" () -> i32 {
+	when thread.IS_SUPPORTED {
+		context = g_ctx
+		thread.yield()
+	}
 	return 0
 }