[patch,build] Build libgfortran and libgomp as DLL on win32

[François-Xavier Coudert]

The attached patch allows libgfortran and libgomp to be built as
shared libraries (DLL) on i386-pc-mingw32. It simply adds
-no-undefined to the linker flags, and checks for support in the
configure.ac: LT_INIT([shared static win32-dll dlopen]).

This was bootstrapped and manually tested on i386-pc-mingw32.
(Building libgomp requires using pthreads-win32 and explicitly
configuring with --enable-libgomp.) I think I need the approval of
build maintainers for this patch, but other opinions are welcome
(especially the windows maintainers).

FX


PS: I intend to do the same for libobjc and libstdc++-v3, but I can't
make it work for libobjc (I'm investigating) and libstdc++-v3 is
currently broken on mingw32. For libssp, I think I'd need some advice:
who maintains it? (there's no listed maintainer AFAICT)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: win32-dll.ChangeLog
Type: application/octet-stream
Size: 562 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/fortran/attachments/20070828/f178a921/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: win32-dll.diff
Type: application/octet-stream
Size: 2136 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/fortran/attachments/20070828/f178a921/attachment-0001.obj>