regress: cleanup some testcases

suite/regress/x64_bigint.py

 #!/usr/bin/python
-# example on how to code a Keystone regression in Python
 # Nguyen Anh Quynh, 2016
 
 # Fill in the information in the form below when you create a new regression

suite/regress/x86_ds_default.py

 #!/usr/bin/python
-# example on how to code a Keystone regression in Python
 # Nguyen Anh Quynh, 2016
 
 # Fill in the information in the form below when you create a new regression

suite/regress/x86_int_3.py

 #!/usr/bin/python
-# example on how to code a Keystone regression in Python
 # Nguyen Anh Quynh, 2016
 
 # Fill in the information in the form below when you create a new regression