Make the install script a little more robust. Addresses #558.

git-svn-id: file:///svn/tokudb@3048 c7de825b-a66e-492c-adef-691d508d4ae1

install.bash

@@ -33,7 +33,7 @@ fi
 targetdir=$prefix/$tokudb-$bdbmajor.$bdbminor
 if [ -d $targetdir ] ; then rm -rf $targetdir ; fi
 
-mkdir $targetdir
+mkdir -p $targetdir
 mkdir $targetdir/include
 cp include/db.h $targetdir/include
 cp include/db_cxx.h $targetdir/include