Add gambit scheme package (#3644)

The Gambit programming system is a full implementation of the Scheme language
which conforms to the R4RS, R5RS and IEEE Scheme standards.

Tested on ARM.

packages/gambit.rb

+require 'package'
+
+class Gambit < Package
+  description 'Efficient implementation of the Scheme programming language'
+  homepage 'http://gambitscheme.org/wiki/index.php/Main_Page'
+  version '4.9.3'
+  source_url 'https://github.com/gambit/gambit/archive/v4.9.3.tar.gz'
+  source_sha256 'a5e4e5c66a99b6039fa7ee3741ac80f3f6c4cff47dc9e0ff1692ae73e13751ca'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system './configure',
+             "--prefix=#{CREW_PREFIX}",
+             "--libdir=#{CREW_LIB_PREFIX}/gambit",
+             '--enable-gcc-opts',
+             '--enable-single-host',
+             '--enable-openssl',
+             '--enable-interpreter-name=gsi-gambit',
+             '--enable-compiler-name=gsc-gambit'
+    system 'make'
+  end
+
+  def self.install
+    system 'make', "DESTDIR=#{CREW_DEST_DIR}", 'install'
+  end
+
+  def self.check
+    system 'make', 'check'
+  end
+end