Add missing TruffleBoundary

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/EmulatedPosixSupport.java

@@ -1537,11 +1537,16 @@ public long[] waitpid(long pid, int options) throws PosixException {
                 throw posixException(OSErrorEnum.ESRCH);
             }
         } catch (InterruptedException e) {
-            Thread.currentThread().interrupt();
+            interruptThread();
             throw posixException(OSErrorEnum.EINTR);
         }
     }
 
+    @TruffleBoundary
+    private static void interruptThread() {
+        Thread.currentThread().interrupt();
+    }
+
     // TODO the implementation of the following builtins is taken from posix.py,
     // do they really make sense for the emulated backend? Is the handling of exist status correct?
 

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonContext.java

@@ -974,6 +974,7 @@ public PythonNativeWrapper getSingletonNativeWrapper(PythonAbstractObject obj) {
         return null;
     }
 
+    @TruffleBoundary
     boolean ownsGil() {
         return globalInterpreterLock.isHeldByCurrentThread();
     }