vips: migrate to pkgconf

Author: cho-m

Formula/v/vips.rb

@@ -22,7 +22,7 @@ class Vips < Formula
   depends_on "gobject-introspection" => :build
   depends_on "meson" => :build
   depends_on "ninja" => :build
-  depends_on "pkg-config" => [:build, :test]
+  depends_on "pkgconf" => [:build, :test]
   depends_on "cairo"
   depends_on "cfitsio"
   depends_on "cgif"
@@ -54,8 +54,6 @@ class Vips < Formula
   uses_from_macos "expat"
   uses_from_macos "zlib"
 
-  fails_with gcc: "5"
-
   def install
     # mozjpeg needs to appear before libjpeg, otherwise it's not used
     ENV.prepend_path "PKG_CONFIG_PATH", Formula["mozjpeg"].opt_lib/"pkgconfig"