(Does not work yet) Build wxMac 2.8.12 on OS X Snow Leopard (10.6.8).

I need some assistance.  It would be desirable to have wxPython for Mac OS X (and other platforms) from Nix, since Apple's policies over the last few years have made it nearly impossible to run applications that require it.

With this recipe I am trying to build wxMac (a dependency of wxPython) version 2.8.12 for Snow Leopard (specifically 10.6.8).

The error produced by the current recipe is:

```
checking if std::basic_string<wchar_t> works... no
configure: error: Can't use --enable-std_string without std::wstring or std::basic_string<wchar_t>
note: keeping build directory `/private/var/folders/3k/3kZI+NsbGHywjqA73FwFE++++TI/-Tmp-/nix-build-wxMac-2.8.12.drv-74'
builder for `/nix/store/bjv0lmvxr0aqj1y5p6jwywlg3xz8sm82-wxMac-2.8.12.drv' failed with exit code 1
error: build of `/nix/store/bjv0lmvxr0aqj1y5p6jwywlg3xz8sm82-wxMac-2.8.12.drv' failed
```

This error is triggered by adding the flag ```--enable-std_string```, without which the configuration completes, but the compilation of ```wxregex_regcomp.o``` fails when it can't include ```stdarg.h```.

[This page](http://www.wxwidgets.org/docs/faqmac.htm#buildx) suggests following the instructions in docs/osx/install.txt of wxMac, and doing:

```
arch_flags="-arch i386"
../configure CFLAGS="$arch_flags" CXXFLAGS="$arch_flags" CPPFLAGS="$arch_flags" LDFLAGS="$arch_flags" OBJCFLAGS="$arch_flags" OBJCXXFLAGS="$arch_flags" --enable-unicode --enable-debug --disable-shared
```

I found that setting the various ```CFLAGS```, ```CXXFLAGS```, etc, in ```configureFlags``` causes all kinds of problems, and does not seem to be necessary, since the resulting config.log shows that the desired architecture is detected automatically, although I'm not sure about that:

```
configure:1725: checking build system type
configure:1743: result: i686-apple-darwin10.8.0
configure:1751: checking host system type
configure:1765: result: i686-apple-darwin10.8.0
configure:1773: checking target system type
configure:1787: result: i686-apple-darwin10.8.0
```

(I am running a MacBook Pro with Intel Core 2 Duo, so it is a 64 bit system).

[This page](http://wiki.wxwidgets.org/Development:_wxMac#Building_under_10.6_Snow_Leopard) has similar advice.