[PATCH] Build libgcc_s on Windows

[Paolo Bonzini]

> 	<toplevel>

Ok, but you forgot a piece of a comment in configure.ac.

> 	* acinclude.m4 <enable_symvers>: Don't use symvers on Windows.

Ok (it is a build patch, so no need to wait for the libstdc++-v3 
maintainers for this kind of patch).

> 	<gcc>
> 	* mkmap-flat.awk: Add option pe_dll.

I think I can approve this part too, which is anyway pretty trivial. 
Given Charles' comments I'd do instead:

+  if (pe_dll) {
+    # This matches SHLIB_SONAME in config/i386/t-cygming.
+    print "LIBRARY " pe_dll;
+    print "EXPORTS";
+  }

so that in the future it will suffice to have Windows maintainer 
approval if you change the soname.

Paolo