conf-gnuplot: Try to fix

Author: clecat

packages/conf-gnuplot/conf-gnuplot.0.1/opam

@@ -16,7 +16,8 @@ depexts: [
   ["gnuplot"] {os-family = "suse" | os-family = "opensuse"}
   ["gnuplot"] {os-family = "arch"}
   ["gnuplot"] {os = "freebsd"}
-  ["gnuplot"] {os = "win32" & os-distribution = "cygwinports"}
+  ["gnuplot-base"] {os = "win32" & os-distribution = "cygwin"}
+  ["mingw-w64-x86_64-gnuplot"] {os = "win32" & os-distribution = "msys2"}
   ["math/gnuplot"] {os = "openbsd"}
 ]
 synopsis: "Virtual package relying on gnuplot installation"