fix invalid library usage

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/exception/PBaseException.java

@@ -315,7 +315,7 @@ String getExceptionMessage(@CachedLibrary("this") PythonObjectLibrary lib) {
 
     @ExportMessage
     int getExceptionExitStatus(
-                    @CachedLibrary("this") PythonObjectLibrary lib,
+                    @CachedLibrary(limit = "2") PythonObjectLibrary lib,
                     @Cached ReadAttributeFromDynamicObjectNode readNode,
                     @Shared("unsupportedProfile") @Cached BranchProfile unsupportedProfile) throws UnsupportedMessageException {
         if (getExceptionType(lib) == ExceptionType.EXIT) {