Changes to configure to recognize MinGW Win32 platform

Hi

I've started to port LLVM to the MinGW Win32 platform.

To successfully recognize the platform, following statements should
be inserted into the configure script:

diff.txt (474 Bytes)

Thanks!

In future, please provide patches to autoconf/configure.ac instead
of configure itself, because configure is generated from
autoconf/configure.ac by using the "autoconf" tool.

-Brian