Scripts: Add {} following -I option to xargs

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1573

wmake/wcleanAll

@@ -69,7 +69,7 @@ rm -rf platforms/*
 
 echo "Cleaning Make sub-directories"
 find . -depth \( -name Make -o -name "Make.[A-Za-z]*" \) -type d -print | \
-    xargs -I find '{}' -mindepth 1 -maxdepth 1 -type d -print | \
+    xargs -I {} find '{}' -mindepth 1 -maxdepth 1 -type d -print | \
     xargs rm -rf
 
 echo "Removing lnInclude directories"

wmake/wcleanMachine

@@ -79,7 +79,7 @@ do
     echo "Cleaning machine type: $machType"
 
     find . -depth \( -name Make -o -name "Make.[A-Za-z]*" \) -type d -print | \
-        xargs -I find '{}' -mindepth 1 -maxdepth 1 \
+        xargs -I {} find '{}' -mindepth 1 -maxdepth 1 \
               \( -type d -name "*$machType" -o -name "*$machType$WM_MPLIB" \) \
               -print | xargs rm -rf