Python 3 - Use the exec function, not the exec statement.

exec statement is gone in Python 3, this version works in both.

llvm-svn: 252347
diff --git a/lldb/packages/Python/lldbsuite/test/lldbinline.py b/lldb/packages/Python/lldbsuite/test/lldbinline.py
index e27cb15..67a5e81 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbinline.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbinline.py
@@ -141,7 +141,7 @@
         self.do_test()
 
     def execute_user_command(self, __command):
-        exec __command in globals(), locals()
+        exec(__command, globals(), locals())
 
     def do_test(self):
         exe_name = "a.out"