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.
* gdb.base/freebpcmd.c: Include <stdio.h>.
* gdb.base/long_long.c: Include <string.h>.
* gdb.base/sigaltstack.c: Include <stdlib.h> <string.h>.
* gdb.base/siginfo.c: Include <string.h>.
* gdb.base/sigstep.c: Include <string.h>.
