Make c_regex_traits all inline.

Fix some C++20 issues.

test/captures/Jamfile.v2

@@ -8,12 +8,8 @@ project
     ;
 
 EX_SOURCES = 
-   c_regex_traits.cpp
    cpp_regex_traits.cpp
-   cregex.cpp
-   fileiter.cpp
    icu.cpp
-   instances.cpp
    posix_api.cpp
    regex.cpp
    regex_debug.cpp
@@ -21,10 +17,7 @@ EX_SOURCES =
    regex_traits_defaults.cpp
    static_mutex.cpp
    w32_regex_traits.cpp
-   wc_regex_traits.cpp
-   wide_posix_api.cpp
-   winstances.cpp 
-   usinstances.cpp ;
+   wide_posix_api.cpp ;
        
 lib boost_regex_extra : $(EX_SOURCES) ../../build//icu_options
     :