Switch to library requirements instead of source. As source puts extr…

…a source in install targets.

build.jam

@@ -7,21 +7,21 @@ import project ;
 
 project /boost/property_map
     : common-requirements
-        <source>/boost/any//boost_any
-        <source>/boost/assert//boost_assert
-        <source>/boost/concept_check//boost_concept_check
-        <source>/boost/config//boost_config
-        <source>/boost/core//boost_core
-        <source>/boost/function//boost_function
-        <source>/boost/iterator//boost_iterator
-        <source>/boost/lexical_cast//boost_lexical_cast
-        <source>/boost/mpl//boost_mpl
-        <source>/boost/smart_ptr//boost_smart_ptr
-        <source>/boost/static_assert//boost_static_assert
-        <source>/boost/throw_exception//boost_throw_exception
-        <source>/boost/type_index//boost_type_index
-        <source>/boost/type_traits//boost_type_traits
-        <source>/boost/utility//boost_utility
+        <library>/boost/any//boost_any
+        <library>/boost/assert//boost_assert
+        <library>/boost/concept_check//boost_concept_check
+        <library>/boost/config//boost_config
+        <library>/boost/core//boost_core
+        <library>/boost/function//boost_function
+        <library>/boost/iterator//boost_iterator
+        <library>/boost/lexical_cast//boost_lexical_cast
+        <library>/boost/mpl//boost_mpl
+        <library>/boost/smart_ptr//boost_smart_ptr
+        <library>/boost/static_assert//boost_static_assert
+        <library>/boost/throw_exception//boost_throw_exception
+        <library>/boost/type_index//boost_type_index
+        <library>/boost/type_traits//boost_type_traits
+        <library>/boost/utility//boost_utility
         <include>include
     ;