Revert "report_errors with expected failures (#51)"

This reverts commit 02041f6c9f and
https://github.com/boostorg/core/pull/51.

Reason for revert: The change allows for incorrect result code returned
from the process if the number of failures is a multiple of 256. This
may result in test failures being taken as success by the parent process.

include/boost/core/lightweight_test.hpp

@@ -383,13 +383,14 @@ inline int report_errors()
     {
         BOOST_LIGHTWEIGHT_TEST_OSTREAM
           << "No errors detected." << std::endl;
+        return 0;
     }
     else
     {
         BOOST_LIGHTWEIGHT_TEST_OSTREAM
           << errors << " error" << (errors == 1? "": "s") << " detected." << std::endl;
+        return 1;
     }
-    return errors;
 }
 
 } // namespace boost

test/Jamfile.v2

@@ -75,6 +75,7 @@ run lightweight_test_gt_ge_test.cpp ;
 run lightweight_test_eq_nullptr.cpp ;
 run lightweight_test_test3.cpp ;
 run lightweight_test_test4.cpp ;
+run lightweight_test_test5.cpp ;
 
 run-fail lightweight_test_all_eq_test.cpp ;
 run-fail lightweight_test_all_with_fail.cpp ;
@@ -92,7 +93,6 @@ run-fail lightweight_test_fail8.cpp : : : <rtti>off : lightweight_test_fail8_no_
 run-fail lightweight_test_fail9.cpp ;
 run-fail lightweight_test_fail10.cpp ;
 run-fail lightweight_test_fail11.cpp ;
-run-fail lightweight_test_fail12.cpp ;
 run-fail lightweight_test_lt_fail.cpp ;
 run-fail lightweight_test_le_fail.cpp ;
 run-fail lightweight_test_gt_fail.cpp ;