Remove more old code and enable standalone mode.

test/Jamfile.v2

@@ -152,7 +152,10 @@ test-suite regex
             <define>BOOST_REGEX_STANDALONE [ check-target-builds ../build//is_legacy_03 : : <source>../build//boost_regex ] : standalone_concept_check
       ]
       [ link concepts/icu_concept_check.cpp :
-            [ check-target-builds ../build//is_legacy_03 : : <source>../build//boost_regex ]
+            <define>BOOST_REGEX_STANDALONE [ check-target-builds ../build//is_legacy_03 : : <source>../build//boost_regex ]
+      ]
+      [ link concepts/icu_concept_check.cpp :
+            [ check-target-builds ../build//is_legacy_03 : : <source>../build//boost_regex ] : standalone_icu_concept_check
       ]
       [ link concepts/range_concept_check.cpp :
             [ check-target-builds ../build//is_legacy_03 : : <source>../build//boost_regex ]

test/regress/test_icu.cpp

@@ -23,6 +23,7 @@
 #if defined(BOOST_HAS_ICU) && !defined(BOOST_NO_STD_WSTRING)
 
 #include <boost/regex/icu.hpp>
+#include <boost/mpl/int.hpp>
 #include "test.hpp"
 
 namespace unnecessary_fix{

test/static_mutex/static_mutex_test.cpp

@@ -22,6 +22,7 @@
 #include <iostream>
 #include <iomanip>
 
+#ifdef BOOST_REGEX_CXX03
 //
 // we cannot use the regular Boost.Test in here: it is not thread safe
 // and calls to BOOST_CHECK will eventually crash on some compilers 
@@ -205,3 +206,6 @@ int main()
 
    return total_failures;
 }
+#else
+int main() {}
+#endif

test/unicode/unicode_iterator_test.cpp

@@ -16,7 +16,12 @@
   *   DESCRIPTION: Simple test suite for Unicode interconversions.
   */
 
-#include <boost/regex/pending/unicode_iterator.hpp>
+#include <boost/regex/config.hpp>
+#ifdef BOOST_REGEX_CXX03
+#include <boost/regex/v4/unicode_iterator.hpp>
+#else
+#include <boost/regex/v5/unicode_iterator.hpp>
+#endif
 #include <boost/detail/lightweight_main.hpp>
 #include "../test_macros.hpp"
 #include <vector>
@@ -317,6 +322,6 @@ int cpp_main( int, char* [] )
    for(unsigned i = 0xDFFF + 1; i < 0x10FFFF; ++i)
       v.push_back(i);
    test(v);
-   return 0;
+   return boost::report_errors();
 }