Cleanup static variables

[zufuliu]

1. static const int hash_value_mask can be changed to static constexpr int hash_value_mask:
   

   regex/include/boost/regex/v5/basic_regex.hpp

   Line 61 in cb55913

   static const int hash_value_mask = 1 << (std::numeric_limits<int>::digits - 1);

2. static on trivial w and s variables can be removed:
   

   regex/include/boost/regex/v5/basic_regex_creator.hpp

   Lines 267 to 268 in cb55913

   	static const charT w = 'w';
   	static const charT s = 's';

3. static const std::uintmax_t one can be changed to constexpr std::uintmax_t one:
   

   regex/include/boost/regex/v5/basic_regex_creator.hpp

   Line 1470 in cb55913

   static const std::uintmax_t one = 1uL;

   
   

   regex/include/boost/regex/v5/basic_regex_creator.hpp

   Line 1490 in cb55913

   static const std::uintmax_t one = 1uL;

4. static const char incomplete_message[] can be changed to const char * const incomplete_message:
   

   regex/include/boost/regex/v5/basic_regex_parser.hpp

   Line 852 in cb55913

   static const char incomplete_message[] = "Incomplete \\g escape found.";

   
   

   regex/include/boost/regex/v5/basic_regex_parser.hpp

   Line 1132 in cb55913

   static const char incomplete_message[] = "Missing } in quantified repetition.";

   
   

   regex/include/boost/regex/v5/basic_regex_parser.hpp

   Line 1338 in cb55913

   static const char incomplete_message[] = "Character set declaration starting with [ terminated prematurely - either no ] was found or the set had no content.";

   
   

   regex/include/boost/regex/v5/basic_regex_parser.hpp

   Line 1430 in cb55913

   static const char incomplete_message[] = "Character class declaration starting with [ terminated prematurely - either no ] was found or the set had no content.";

5. static const bool value can be changed to static constexpr bool value:
   

   regex/include/boost/regex/v5/iterator_category.hpp

   Line 36 in cb55913

   static const bool value = (std::is_convertible<cat*, std::random_access_iterator_tag*>::value);

   
   

   regex/include/boost/regex/v5/iterator_category.hpp

   Line 42 in cb55913

   static const bool value = true;

   
   

   regex/include/boost/regex/v5/iterator_category.hpp

   Line 75 in cb55913

   static const bool value = answer::value;

6. const bool is_random_access_iterator can be changed to constexpr bool is_random_access_iterator:
   

   regex/include/boost/regex/v5/iterator_category.hpp

   Line 79 in cb55913

   const bool is_random_access_iterator<I>::value;

   
   these two lines can be removed after change line 75 to constexpr.

7. static const std::ptrdiff_t k can be changed to constexpr std::ptrdiff_t k:
   

   regex/include/boost/regex/v5/perl_matcher_common.hpp

   Line 104 in cb55913

   static const std::ptrdiff_t k = 100000;

8. static const bool value can be changed to static constexpr bool value:
   

   regex/include/boost/regex/v5/regex_traits.hpp

   Line 59 in cb55913

   static const bool value = sizeof(checker(get())) > 1;

9. big array const char* messages[] can be marked as static:
   

   regex/include/boost/regex/v5/regex_traits_defaults.hpp

   Line 53 in cb55913

   const char* messages[] = {

10. big array char_syntax[] can be marked as const:
    

    regex/include/boost/regex/v5/regex_traits_defaults.hpp

    Line 158 in cb55913

    static regex_constants::syntax_type char_syntax[] = {

    
    

    regex/include/boost/regex/v5/regex_traits_defaults.hpp

    Line 353 in cb55913

    static regex_constants::escape_syntax_type char_syntax[] = {

11. big array combining_ranges[] can be marked as static:
    

    regex/include/boost/regex/v5/regex_traits_defaults.hpp

    Line 545 in cb55913

    const std::uint_least16_t combining_ranges[] = { 0x0300, 0x0361,

12. static const for trivial variables can be changed to constexpr:
    

    regex/include/boost/regex/v5/regex_traits_defaults.hpp

    Lines 897 to 902 in cb55913

    	static const charT zero = '0';
    	static const charT nine = '9';
    	static const charT a = 'a';
    	static const charT f = 'f';
    	static const charT A = 'A';
    	static const charT F = 'F';

13. static const char_class_type can be change to static constexpr char_class_type:
    

    regex/include/boost/regex/v5/w32_regex_traits.hpp

    Lines 411 to 415 in cb55913

    	static const char_class_type mask_word = 0x0400; // must be C1_DEFINED << 1
    	static const char_class_type mask_unicode = 0x0800; // must be C1_DEFINED << 2
    	static const char_class_type mask_horizontal = 0x1000; // must be C1_DEFINED << 3
    	static const char_class_type mask_vertical = 0x2000; // must be C1_DEFINED << 4
    	static const char_class_type mask_base = 0x3ff; // all the masks used by the CT_CTYPE1 group

14. static const string_type null_string; can be changed to constexpr string_type null_string; const string_type null_string;:
    

    regex/include/boost/regex/v5/w32_regex_traits.hpp

    Line 589 in cb55913

    static const string_type null_string;

[zufuliu]

With these changes, Notepad2 built by MSVC is 1KB~2KB smaller.