vbox5: use sched_yield instead of pthread_yield

Fixes #2551

repos/ports/ports/virtualbox5.hash

@@ -1 +1 @@
-e060302687a8d4233ce5b0304a30a7ee59e8d0af
+c916354430e16892bbc739aaecd86b9451860326

repos/ports/src/virtualbox5/accloff/sup.cc

@@ -28,6 +28,8 @@
 
 /* Libc include */
 #include <pthread.h>
+#include <sched.h> /* sched_yield */
+
 
 /* VirtualBox SUPLib interface */
 
@@ -130,7 +132,11 @@ HRESULT genode_setup_machine(ComObjPtr<Machine> machine)
 }
 
 
-extern "C" void pthread_yield() { Genode::warning(__func__, " unimplemented"); }
+extern "C" int sched_yield(void)
+{
+	Genode::warning(__func__, " unimplemented");
+	return -1;
+}
 
 int SUPR3PageAllocEx(::size_t cPages, uint32_t fFlags, void **ppvPages,
                      PRTR0PTR pR0Ptr, PSUPPAGE paPages)

repos/ports/src/virtualbox5/patches/vbox_main.patch

@@ -1057,21 +1057,6 @@ index a717aff..3d52b9f 100644
      int rc = RTLogGroupSettings(RTLogRelGetDefaultInstance(), useLoggingLevel.c_str());
      //  If failed and not the default logging level - try to use the default logging level.
      if (RT_FAILURE(rc))
---- a/src/app/virtualbox/src/VBox/Runtime/r3/posix/semevent-posix.cpp
-+++ b/src/app/virtualbox/src/VBox/Runtime/r3/posix/semevent-posix.cpp
-@@ -49,10 +49,12 @@
- # define pthread_yield() pthread_yield_np()
- #endif
- 
-+#if 0
- #if defined(RT_OS_SOLARIS) || defined(RT_OS_HAIKU) || defined(RT_OS_FREEBSD) || defined(RT_OS_NETBSD)
- # include <sched.h>
- # define pthread_yield() sched_yield()
- #endif
-+#endif
- 
- 
- /*********************************************************************************************************************************
 --- a/src/app/virtualbox/src/VBox/Main/src-client/BusAssignmentManager.cpp
 +++ b/src/app/virtualbox/src/VBox/Main/src-client/BusAssignmentManager.cpp
 @@ -71,6 +71,8 @@

repos/ports/src/virtualbox5/spec/nova/sup.cc

@@ -41,6 +41,9 @@
 /* libc memory allocator */
 #include <libc_mem_alloc.h>
 
+/* libc */
+#include <sched.h> /* sched_yield */
+
 #include "mm.h"
 
 
@@ -753,9 +756,9 @@ bool PGMUnmapMemoryGenode(void * vmm_local, ::size_t size)
 }
 
 
-extern "C" void pthread_yield(void)
+extern "C" int sched_yield(void)
 {
-	Nova::ec_ctrl(Nova::EC_YIELD);
+	return (Nova::ec_ctrl(Nova::EC_YIELD) == Nova::NOVA_OK) ? 0 : -1;
 }