perl-5.11.2 breaks NYTProf savesrc option (Lexer API suspected)

perl-5.11.2 breaks NYTProf savesrc option (Lexer API suspected)

Tim Bunce wrote:
>The primary issue is the off-by-one error in the array indexing.

There's a bit more to it than that.  The indexing was off-by-one for
*some* places that process a new line, but correct for others, so the
saved source as a whole was mangled rather than simply offset.  Also,
there were some redundant calls to update_debugger_info(), so some lines
got saved twice, in some cases off-by-one for one saving and not for
the other.  The saved source is, therefore, hopelessly broken in 5.11.2.

Attached patch fixes the source saving.  Includes a new test, which works
through all reachable places that source lines get saved.  This should
close RT #70804.

-zefram