Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
directives to conditionalize symbol prefixing.
* gdb.arch/i386-prologue.exp: Allow symbol prefixing by adding
additional_flags handling. Add underscore prefix for Cygwin.
* gdb.arch/i386-unwind.c: Use preprocessor directives to
conditionalize symbol prefixing.
* gdb.arch/i386-unwind.exp: Allow symbol prefixing by adding
additional_flags handling. Add underscore prefix for Cygwin.
