Enable forced 32-bit build on Windows

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/README b/README
index 4c7b542..4173237 100644
--- a/README
+++ b/README
@@ -125,6 +125,9 @@
  5. Run 'make clean'.
  6. Run 'make'.
 
+To build fio on 32-bit Windows, download x86/pthreadGC2.dll instead and do
+'./configure --build-32bit-win=yes' before 'make'.
+
 
 Command line
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