Add component openvpn for cygwin.

component/openvpn/buildout.cfg

+[buildout]
+parts =
+  openvpn
+
+[openvpn]
+recipe = slapos.recipe.cmmi
+url = http://swupdate.openvpn.org/community/releases/openvpn-2.3.0.tar.gz
+md5sum = 56cffde5d5320e0b1ec364d3e486aca9
+
+[x86-cygwin-zlib]
+share = /usr/local
+promises = /usr/local/bin/openvpn.exe
+configure-options =
+  ac_cv_type_socklen_t=yes
+  IFCONFIG="${SYSTEMDRIVE}:/WINDOWS/system32"
+  LDFLAGS="-liphlpapi -lws2_32"
+  CFLAGS="-DWIN32 -DCYGWIN -D__USE_W32_SOCKETS -D__INSIDE_CYGWIN_NET__ -DWIN32_LEAN_AND_MEAN -D_WIN32_WINNT=0x0503"
+  --disable-lzo
+  --disable-pkcs11
+  --disable-plugin-auth-pam
+  --disable-plugin-down-root
+
+patch-options = -p1
+patches =
+  ${:_profile_base_location_}/openvpn-2.3.0-cygwin.patch
+