Updated configuration for Embarcadero C++ clang-based compilers. Created a better test for CWCHAR compatibility which involves a minimum of multi-byte character functionality also.

test/boost_no_cwchar.ipp

@@ -18,6 +18,9 @@ int test()
 {
    wchar_t c1[2] = { 0 };
    wchar_t c2[2] = { 0 };
+   char    c3[2] = { 0 };
+   mbstate_t mb = mbstate_t();
+   if(!mbsinit(&mb) || mbrlen(c3,1,&mb)) return -1;
    if(wcscmp(c1,c2) || wcslen(c1)) return -1;
    //wcscpy(c1,c2);
    wcsxfrm(c1,c2,0);