Split out older testsuite/ChangeLog entries (prior to 2014)
into separate file: ChangeLog-1993-2013.
Add link to older changes in ChangeLog-1993-2013.
Support 32->64 sign extension in msp430's sign_ext

* msp43-sim.c (sign_ext): Change to "long long" to support
sign-extending 32-bit values.