Added SwitchToThread.

diff --git a/dlls/kernel/kernel32.spec b/dlls/kernel/kernel32.spec
index c12f4db..988c4b6 100644
--- a/dlls/kernel/kernel32.spec
+++ b/dlls/kernel/kernel32.spec
@@ -937,7 +937,7 @@
 @ stdcall SetWaitableTimer(long ptr long ptr ptr long) SetWaitableTimer
 @ stub SignalObjectAndWait
 @ stub SwitchToFiber
-@ stub SwitchToThread
+@ stdcall SwitchToThread() SwitchToThread
 @ forward TryEnterCriticalSection ntdll.RtlTryEnterCriticalSection
 @ stdcall VirtualAllocEx(long ptr long long long) VirtualAllocEx
 @ stub VirtualFreeEx
diff --git a/dlls/kernel/kernel_main.c b/dlls/kernel/kernel_main.c
index b3318d6..2469103 100644
--- a/dlls/kernel/kernel_main.c
+++ b/dlls/kernel/kernel_main.c
@@ -155,3 +155,9 @@
 {
     return 0;
 }
+
+BOOL WINAPI SwitchToThread(VOID)
+{
+    Sleep(0);
+    return 1;
+}