Use mkdir() instead of !mkdir in test 73, it's more reliable.

src/testdir/Make_dos.mak

@@ -59,8 +59,6 @@ clean:
 	-if exist mbyte.vim del mbyte.vim
 	-if exist mzscheme.vim del mzscheme.vim
 	-del X*
-	-del X*.*
-	-if exists Xfind rmdir /S /Q Xfind
 	-if exist viminfo del viminfo
 
 .in.out:
@@ -72,4 +70,5 @@ clean:
 	-del X*
 	-del X*.*
 	-del test.ok
+	-rmdir /s /q Xfind
 	-if exist viminfo del viminfo

src/testdir/test73.in

@@ -22,7 +22,7 @@ STARTTEST
 :new
 :let cwd=getcwd()
 :let test_out = cwd . '/test.out'
-:silent !mkdir Xfind
+:call mkdir('Xfind')
 :cd Xfind
 :set path=
 :find 	
@@ -45,9 +45,9 @@ STARTTEST
 :close
 :new
 :" We shouldn't find any file at this point, test.out must be empty.
-:silent !mkdir in
+:call mkdir('in')
 :cd in
-:silent !mkdir path
+:call mkdir('path')
 :exec "cd " . cwd
 :e Xfind/file.txt
 SHoly Grail:w
@@ -103,15 +103,15 @@ SE.T.:w
 :"
 :"    x/bar/voyager.txt
 :"    y/bar/voyager.txt
-:silent !mkdir foo
+:call mkdir('foo')
 :cd foo
-:silent !mkdir x
-:silent !mkdir y
+:call mkdir('x')
+:call mkdir('y')
 :cd x
-:silent !mkdir bar
+:call mkdir('bar')
 :cd ..
 :cd y
-:silent !mkdir bar
+:call mkdir('bar')
 :cd ..
 :cd ..
 :" We should now be in the Xfind directory