* History saving should stay disabled for test cases *

I saw some test cases in gdb.base/default.exp and gdb.base/setshow.exp
are enabling the history saving.
Hence .gdb_history file is modified with history information even
though, by default, we have History saving disabled.
So we should modify GDB test cases so that history saving should stay
off for all test cases.



ChangeLog:

2013-05-13  Muhammad Bilal  <mbilal@codesourcery.com>

       * gdb.base/default.exp: Disable history saving.
       * gdb.base/setshow.exp: Likewise.