Add pkgconf (#4698)

* Add pkgconf

* Use github links

packages/pkgconf.rb

+require 'package'
+
+class Pkgconf < Package
+  description 'Package compiler and linker metadata toolkit'
+  homepage 'https://github.com/pkgconf/pkgconf'
+  version '1.7.3'
+  compatibility 'all'
+  source_url 'https://github.com/pkgconf/pkgconf/archive/pkgconf-1.7.3.tar.gz'
+  source_sha256 '8f2c6e9f08adc5773d7fa3c1db1ed03f5fa02ceed037a537ce1195f7c93700ed'
+
+  depends_on 'glibc'
+
+# Can be enabled for packages by setting
+# ENV['PKG_CONFIG'] = "#{CREW_PREFIX}/bin/pkgconf"
+
+def self.build
+    system "./autogen.sh"
+    system "./configure #{CREW_OPTIONS} \
+    --with-system-libdir=#{CREW_LIB_PREFIX} \
+    --with-system-includedir=#{CREW_PREFIX}/include"
+    system "make"
+  end
+  
+  def self.install
+    system "make DESTDIR=#{CREW_DEST_DIR} install"
+  end
+end