upgrade to 2019.10

Formula/vcpkg.rb

@@ -2,24 +2,20 @@ class Vcpkg < Formula
   desc "C++ Library Manager for Windows, Linux, and MacOS"
   homepage "https://docs.microsoft.com/en-us/cpp/vcpkg"
 
-  url "https://github.com/microsoft/vcpkg/archive/2019.09.tar.gz"
-  sha256 "16c1b151cc3cf2022b03b699970e548f48cd9cd1e68db0b9c23a1d0d39391e56"
+  url "https://github.com/microsoft/vcpkg/archive/2019.10.tar.gz"
+  sha256 "1a3e81b50702522ede10806f38d929d9aa4c7ffb5c2595eeee07a04cafacc77c"
   head "https://github.com/microsoft/vcpkg.git"
 
   depends_on "cmake" => :build
   depends_on "ninja" => :build
-  depends_on "gcc"
 
   def install
-    ENV["CC"] = Formula["gcc"].opt_bin/"gcc-#{Formula["gcc"].version_suffix}"
-    ENV["CXX"] = Formula["gcc"].opt_bin/"g++-#{Formula["gcc"].version_suffix}"
-    system "./bootstrap-vcpkg.sh", "-useSystemBinaries"
+    system "./bootstrap-vcpkg.sh", "-useSystemBinaries", "-allowAppleClang"
     libexec.install ["ports", "scripts", "triplets", "vcpkg", ".vcpkg-root"]
     bin.install_symlink libexec/"vcpkg"
   end
 
   test do
-    assert_match version.to_s, pipe_output("#{bin}/vcpkg version")
     assert_match "zlib", pipe_output("#{bin}/vcpkg search zlib")
   end
 end