Update units from 2.14 to 2.15

This is a bugfix and maintenance release.

Tested as working on Samsung Chromebook Plus (ARMv8).

packages/units.rb

@@ -3,16 +3,17 @@ require 'package'
 class Units < Package
   description 'GNU Units converts quantities expressed in various systems of measurement to their equivalents in other systems of measurement.'
   homepage 'https://www.gnu.org/software/units/units.html'
-  version '2.14'
-  source_url 'https://ftp.gnu.org/gnu/units/units-2.14.tar.gz'
-  source_sha256 '9d33893d82f3ddd831d5822992007c40bcd0826ae67d3cbc96539951fb0a82e8'
+  version '2.15'
+  source_url 'https://ftp.gnu.org/gnu/units/units-2.15.tar.gz'
+  source_sha256 '25d6334fafc801e15b3b0388e207e1efc5d4ae88af6dc7b17d3913de6441f47c'
 
   def self.build
-    system './configure'
+    system './configure',
+      "--prefix=#{CREW_PREFIX}"
     system 'make'
   end
 
   def self.install
-    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+    system 'make', "DESTDIR=#{CREW_DEST_DIR}", 'install'
   end
 end