RFR: JDK-8196911: Windows build fails with not finding zlib.h

[Erik Joelsson]

A small typo managed to sneak itself into my previous patch, causing the 
build to fail on Windows.

Bug: https://bugs.openjdk.java.net/browse/JDK-8196911

Patch inline:

diff -r 0b1138ce244f make/autoconf/lib-bundled.m4
--- a/make/autoconf/lib-bundled.m4      Tue Feb 06 10:17:31 2018 -0800
+++ b/make/autoconf/lib-bundled.m4      Tue Feb 06 22:34:12 2018 +0100
@@ -209,7 +209,7 @@
      AC_MSG_ERROR([Invalid value for --with-zlib: ${with_zlib}, use 
'system' or 'bundled'])
    fi

-  if test "x$USER_EXTERNAL_LIBZ" = "xfalse"; then
+  if test "x$USE_EXTERNAL_LIBZ" = "xfalse"; then
      LIBZ_CFLAGS="$LIBZ_CFLAGS 
-I$TOPDIR/src/java.base/share/native/libzip/zlib"
    else
      LIBZ_LIBS="-lz"

/Erik