Switch to library requirements instead of source. As source puts extra source in install targets.

Author: grafikrobot

build.jam

@@ -7,22 +7,22 @@ import project ;
 
 project /boost/signals2
     : common-requirements
-        <source>/boost/assert//boost_assert
-        <source>/boost/bind//boost_bind
-        <source>/boost/config//boost_config
-        <source>/boost/core//boost_core
-        <source>/boost/function//boost_function
-        <source>/boost/iterator//boost_iterator
-        <source>/boost/mpl//boost_mpl
-        <source>/boost/optional//boost_optional
-        <source>/boost/parameter//boost_parameter
-        <source>/boost/predef//boost_predef
-        <source>/boost/preprocessor//boost_preprocessor
-        <source>/boost/smart_ptr//boost_smart_ptr
-        <source>/boost/throw_exception//boost_throw_exception
-        <source>/boost/tuple//boost_tuple
-        <source>/boost/type_traits//boost_type_traits
-        <source>/boost/variant//boost_variant
+        <library>/boost/assert//boost_assert
+        <library>/boost/bind//boost_bind
+        <library>/boost/config//boost_config
+        <library>/boost/core//boost_core
+        <library>/boost/function//boost_function
+        <library>/boost/iterator//boost_iterator
+        <library>/boost/mpl//boost_mpl
+        <library>/boost/optional//boost_optional
+        <library>/boost/parameter//boost_parameter
+        <library>/boost/predef//boost_predef
+        <library>/boost/preprocessor//boost_preprocessor
+        <library>/boost/smart_ptr//boost_smart_ptr
+        <library>/boost/throw_exception//boost_throw_exception
+        <library>/boost/tuple//boost_tuple
+        <library>/boost/type_traits//boost_type_traits
+        <library>/boost/variant//boost_variant
         <include>include
     ;