Cygwin: dllfixdbg: create .gnu_debuglink section in the right spot

A recent change in binutils marks the .gnu_debuglink_overlay section
as debug section.  When dllfixdbg calls objcopy -g, the section
is removed and the --add-gnu-debuglink option on the same command line
appends the section consequentially at the end of the sections.
This in turn breaks Windows Version info and, potentially, raising
the cygheap size at runtime.

Fix this by adding an explicit --keep-section=.gnu_debuglink_overlay
to the objcopy command line.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/dllfixdbg

@@ -16,7 +16,7 @@ my @objcopy = ((shift));
 my $dll = shift;
 my $dbg = shift;
 xit 0, @objcopy, '-R', '.gnu_debuglink_overlay', '--add-gnu-debuglink=/dev/null', '--only-keep-debug', $dll, $dbg;
-xit 0, @objcopy, '-g', '--add-gnu-debuglink=' . $dbg, $dll;
+xit 0, @objcopy, '-g', '--keep-section=.gnu_debuglink_overlay', '--add-gnu-debuglink=' . $dbg, $dll;
 open(OBJDUMP, '-|', "$objdump --headers $dll");
 my %section;
 while (<OBJDUMP>) {

winsup/cygwin/release/3.3.3

@@ -9,3 +9,6 @@ Bug Fixes
   fstatat and other ...at calls.  "X:/" still is handled as absolute
   path.
   Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249837.html
+
+- Fix showing DLL version info from native Windows tools.
+  Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249867.html