Make the library modular usable.

Jamfile

@@ -1,10 +0,0 @@
-#  Boost.Rational Library Jamfile
-#
-#  Copyright (c) 2018 James E. King III
-#
-#  Use, modification, and distribution are subject to the
-#  Boost Software License, Version 1.0. (See accompanying file
-#  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-
-# please order by name to ease maintenance
-build-project test ;

build.jam

@@ -0,0 +1,27 @@
+# Copyright René Ferdinand Rivera Morell 2023
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+# http://www.boost.org/LICENSE_1_0.txt)
+
+import project ;
+
+project /boost/rational
+    : common-requirements
+        <source>/boost/assert//boost_assert
+        <source>/boost/config//boost_config
+        <source>/boost/core//boost_core
+        <source>/boost/integer//boost_integer
+        <source>/boost/static_assert//boost_static_assert
+        <source>/boost/throw_exception//boost_throw_exception
+        <source>/boost/type_traits//boost_type_traits
+        <source>/boost/utility//boost_utility
+        <include>include
+    ;
+
+explicit
+    [ alias boost_rational ]
+    [ alias all : boost_rational test ]
+    ;
+
+call-if : boost-library rational
+    ;

test/Jamfile.v2

@@ -3,7 +3,7 @@
 #~ (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 import testing ;
-import ../../config/checks/config : requires ;
+import config : requires ;
 
 test-suite rational
     :   [ run rational_example.cpp ]