gdb, infcmd: Support jump command with same line in multiple symtabs

If a header file defining a static function is included in multiple source
files, each calling the function, and GDB is asked to jump to a line inside
that function, there would be multiple locations matching the target.  The
solution in this commit is to select the location in the current symtab.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Andrew Burgess <aburgess@redhat.com>