Check inplace doesn't exist before we try to create it

This fixes rerunning configure in a tree which already has an inplace
directory. Edward Z Yang ran into this; I guess whether it actually
fails depends on details of your installation, or we'd have run into
it sooner.

diff --git a/configure.ac b/configure.ac
index db268ab..600317d 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -438,7 +438,7 @@ then
     then
         AC_MSG_NOTICE([Making in-tree mingw tree])
         rm -rf inplace/mingw
-        mkdir inplace
+        test -d inplace || mkdir inplace
         mkdir inplace/mingw
         (
             cd inplace/mingw &&