Kill more warnings from the SGI compiler.

Part of SF patch #434992.

Objects/fileobject.c

@@ -473,7 +473,7 @@ static size_t
 new_buffersize(PyFileObject *f, size_t currentsize)
 {
 #ifdef HAVE_FSTAT
-	long pos, end;
+	off_t pos, end;
 	struct stat st;
 	if (fstat(fileno(f->f_fp), &st) == 0) {
 		end = st.st_size;

Objects/intobject.c

@@ -645,7 +645,7 @@ int_lshift(PyIntObject *v, PyIntObject *w)
 	if (b >= LONG_BIT) {
 		return PyInt_FromLong(0L);
 	}
-	a = (unsigned long)a << b;
+	a = (long)((unsigned long)a << b);
 	return PyInt_FromLong(a);
 }