configure: add default compiler on Windows

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/configure b/configure
index 5dcfe7b..7c12b01 100755
--- a/configure
+++ b/configure
@@ -147,6 +147,9 @@
   ;;
 CYGWIN*)
   echo "Forcing known good options on Windows"
+  if test -z "$CC" ; then
+    CC="x86_64-w64-mingw32-gcc"
+  fi
   echo "CC=$CC"                    >  $config_host_mak
   echo "CONFIG_LITTLE_ENDIAN=y"    >> $config_host_mak
   echo "CONFIG_64BIT_LLP64=y"      >> $config_host_mak