ruby : make Ruby bindings installed with build options (#3056)

* Fix signature of URI.new7s return value

* Use path instead of string | _ToPath

* Add document comment to RBS

* Remove unnecessary build flags

* Remove unnecessary line

* Remove files have become unnecessary

* Make gem install accept build options for whisper.cpp

* Add instraction for build options in README

* Add methods for check to Options

* Test build options

* Rename: configs -> options

* Add assert_installed assertion

* Use assert_installed

* Remove unused attribute

* Extract dependency check logic as Dependencies class

* Update README

* Add WHISPER_FFMPEG option

* Test extra build options only on local test

* Bump version to 1.3.2 [skip ci]

bindings/ruby/ext/dependencies.rb

@@ -0,0 +1,61 @@
+require "tsort"
+
+class Dependencies
+  def initialize(cmake, options)
+    @cmake = cmake
+    @options = options
+
+    generate_dot
+    @libs = parse_dot
+  end
+
+  def to_s
+    @libs.join(" ")
+  end
+
+  private
+
+  def dot_path
+    File.join(__dir__, "build", "whisper.cpp.dot")
+  end
+
+  def generate_dot
+    system @cmake, "-S", "sources", "-B", "build", "--graphviz", dot_path, "-D", "BUILD_SHARED_LIBS=OFF", @options.to_s, exception: true
+  end
+
+  def parse_dot
+    static_lib_shape = nil
+    nodes = {}
+    depends = Hash.new {|h, k| h[k] = []}
+
+    class << depends
+      include TSort
+      alias tsort_each_node each_key
+      def tsort_each_child(node, &block)
+        fetch(node, []).each(&block)
+      end
+    end
+
+    File.open(dot_path).each_line do |line|
+      case line
+      when /\[\s*label\s*=\s*"Static Library"\s*,\s*shape\s*=\s*(?<shape>\w+)\s*\]/
+        static_lib_shape = $~[:shape]
+      when /\A\s*"(?<node>\w+)"\s*\[\s*label\s*=\s*"(?<label>\S+)"\s*,\s*shape\s*=\s*(?<shape>\w+)\s*\]\s*;\s*\z/
+        node = $~[:node]
+        label = $~[:label]
+        shape = $~[:shape]
+        nodes[node] = [label, shape]
+      when /\A\s*"(?<depender>\w+)"\s*->\s*"(?<dependee>\w+)"/
+        depender = $~[:depender]
+        dependee = $~[:dependee]
+        depends[depender] ||= []
+        depends[depender] << dependee
+      end
+    end
+    depends.tsort.filter_map {|node|
+      label, shape = nodes[node]
+      shape == static_lib_shape ? label : nil
+    }.collect {|lib| "lib#{lib}.a"}
+      .reverse
+  end
+end