install-sh patch for cygwin

[greg andruk]

In case I forget to mention it later on, any cygwin patches will be for 
CURRENT.

No idea who originally came up with this patch, it's kinda floating 
around out there in MIT-style installs.

--- install-sh.orig     1999-11-25 23:28:40.000000000 -0500
+++ install-sh  2002-08-30 21:58:16.000000000 -0400
@@ -124,6 +124,11 @@
         true
  fi

+# For Cygwin compatibility.
+if [ -x "$src".exe ]; then
+       src=${src}.exe
+fi
+
  if [ x"$dir_arg" != x ]; then
         dst=$src
         src=""