patch 8.0.0576: can't build when configure choses "install-sh"

Problem:    Can't build when configure choses "install-sh". (Daniel Hahler)
Solution:   Always use install-sh.  Fix remaining use of mkinstalldirs.
            (closes #1647)

src/installml.sh

@@ -49,7 +49,7 @@ eviewname=$9
 if test $what = "install" -a \( -f $destdir/$vimname.1 -o -f $destdir/$vimdiffname.1 -o -f $destdir/$eviewname.1 \); then
    if test ! -d $destdir; then
       echo creating $destdir
-      ./mkinstalldirs $destdir
+      /bin/sh install-sh -c -d $destdir
    fi
 
    # ex