fix(requirements): make script compatible with Ruby 2.3.0 and later

README.md

@@ -53,6 +53,12 @@ The build produced does have some limitations:
   ```
   brew bundle
   ```
+- Ruby 2.3.0 or later is needed to execute the build script itself. macOS comes
+  with Ruby, check your version with `ruby --version`. If it's too old, you can
+  install a newer version with:
+  ```
+  brew install ruby
+  ```
 
 ## Usage
 

build-emacs-for-macos

@@ -172,11 +172,11 @@ class Build
   end
 
   def supports_native_comp?
-    @supports_native_comp ||= configure_help.match?(/\s+--with-nativecomp\s+/)
+    @supports_native_comp ||= !!configure_help.match(/\s+--with-nativecomp\s+/)
   end
 
   def supports_xwidgets?
-    @supports_xwidgets ||= configure_help.match?(/\s+--with-xwidgets\s+/)
+    @supports_xwidgets ||= !!configure_help.match(/\s+--with-xwidgets\s+/)
   end
 
   def detect_native_comp