update pkg-config system package name for rhel and centos 8 and above

packages/conf-pkg-config/conf-pkg-config.1.2/opam

@@ -0,0 +1,40 @@
+opam-version: "2.0"
+maintainer: "[email protected]"
+authors: ["Francois Berenger"]
+homepage: "http://www.freedesktop.org/wiki/Software/pkg-config/"
+bug-reports: "https://github.com/ocaml/opam-repository/issues"
+license: "GPL-1.0-or-later"
+build: [
+  ["pkg-config" "--help"]
+]
+install: [
+  ["ln" "-s" "/usr/local/bin/pkgconf" "%{bin}%/pkg-config"] {os = "openbsd"}
+]
+remove: [
+  ["rm" "-f" "%{bin}%/pkg-config"] {os = "openbsd"}
+]
+post-messages: [
+  "conf-pkg-config: A symlink to /usr/local/bin/pkgconf has been installed in the OPAM bin directory (%{bin}%) on your PATH as 'pkg-config'. This is necessary for correct operation." {os = "openbsd"}
+]
+depexts: [
+  ["pkg-config"] {os-family = "debian"}
+  ["pkg-config"] {os-distribution = "arch"}
+  ["pkgconfig"] {os-distribution = "fedora"}
+  ["pkgconfig"] {os-distribution = "centos" & os-version <= "7"}
+  ["pkgconfig"] {os-distribution = "mageia"}
+  ["pkgconfig"] {os-distribution = "rhel" & os-version <= "7"}
+  ["pkgconfig"] {os-distribution = "ol"}
+  ["pkgconfig"] {os-distribution = "alpine"}
+  ["pkgconfig"] {os-distribution = "nixos"}
+  ["devel/pkgconf"] {os = "openbsd"}
+  ["pkg-config"] {os = "macos" & os-distribution = "homebrew"}
+  ["pkgconf"] {os = "freebsd"}
+  ["pkgconf-pkg-config"] {os-distribution = "rhel" & os-version >= "8"}
+  ["pkgconf-pkg-config"] {os-distribution = "centos" & os-version >= "8"}
+  ["pkg-config"] {os-distribution = "cygwinports"}
+]
+synopsis: "Virtual package relying on pkg-config installation"
+description: """
+This package can only install if the pkg-config package is installed
+on the system."""
+flags: conf