[bug-gnu-libiconv] Description of issues with x86 build for Windows

[Corey Stinson]

Hello,

Maintainers may be aware that building libiconv 1.16 in a Windows 
environment for x64 and x86 is broken for MSVC.

There are a couple of issues.

1)

libcharset's relocatable_stub.c appears to be missing a 
LIBCHARSET_DLL_EXPORT declaration for that function causing a build failure.

2)

The compilation to object format for resource files in ~/src and ~/lib 
fail for the x86 version of the build.  It did work for me on the x64 
build, but seemingly only because I happened to have a copy of 'windres' 
in my path from a Strawberry Perl installation. Absent the Perl 
installation I don't believe I would have a copy of 'windres' on my 
system and the build instructions don't mention needing it.  Lacking it 
results in a very non-intuitive error from libtool.

At some point the configure process uses windres via libtool to compile 
~/windows/libiconv.rc  to ~/lib/libiconv.res, then the make process 
subsequently compiles libiconv.res to ~/.libs/libiconv.res.obj.  When 
windres isn't provided with a --target it compiles the object to its 
built-in default, which in my case was x64, even though all of the other 
C-compiled artifacts are being correctly compiled to x86.  Link failure 
follows.

A similar issue occurs with ~/src/iconv.res.  However, in this case the 
make process uses windres to compile ~/windows/iconv.rc directly to 
object format (but with the .res extension).  Same problem, a 64-bit 
object is generated.

Potential solutions: windres could be fed the --target options. Had 
trouble attempting to do this manually through the make process as 
libtool wasn't cooperating.

Eventually manually generated the necessary files using the MSVC 
toolchain: rc and cvtres.

Lacking knowledge of the inner workings of autotools/configure/libtool 
I'm unclear as to how to resolve this in anything approaching a clever 
way.  Perhaps the above info will be useful to someone else?