Fix memset for unix

core/runtime/procs_unix.odin

@@ -0,0 +1,15 @@
+//+build linux, darwin
+package runtime
+
+@(link_name="memset")
+memset :: proc "c" (ptr: rawptr, val: i32, len: int) -> rawptr {
+	b := byte(val);
+
+	p_start := uintptr(ptr);
+	p_end := p_start + uintptr(max(len, 0));
+	for p := p_start; p < p_end; p += 1 {
+		(^byte)(p)^ = b;
+	}
+
+	return ptr;
+}