ensmallen: use modern cmake syntax

Signed-off-by: Rui Chen <[email protected]>

Formula/e/ensmallen.rb

@@ -14,10 +14,9 @@ class Ensmallen < Formula
  depends_on "armadillo"
 
  def install
- mkdir "build" do
- system "cmake", "..", *std_cmake_args
- system "make", "install"
- end
+ system "cmake", "-S", ".", "-B", "build", *std_cmake_args
+ system "cmake", "--build", "build"
+ system "cmake", "--install", "build"
  end
 
  test do
@@ -33,6 +32,7 @@ def install
  return 0;
  }
  EOS
+
  system ENV.cxx, "test.cpp", "-std=c++11", "-I#{include}", "-L#{Formula["armadillo"].opt_lib}",
  "-larmadillo", "-o", "test"
  end