Change definions in 'reiconv.hpp' to constexpr.

	修改：     ChangeLog
	修改：     include/cppp/reiconv.hpp.in

Author: ChenPi11

ChangeLog

@@ -12,6 +12,7 @@
 	Move generated file into 'lib/generated'.
 	Move cppp-reiconv to a C++ library.
 	Remove translit support.
+	Remove 'LIBICONV_PLUG'.
 
 2023-06-29  Bruno Haible  <bruno@clisp.org>
 

include/cppp/reiconv.hpp.in

@@ -136,22 +136,22 @@ extern "C++"
 
       /* Surfaces.
          The concept of surfaces is described in the 'recode' manual.  */
-      #define ICONV_SURFACE_NONE             0
+      constexpr int ICONV_SURFACE_NONE = 0;
       /* In EBCDIC encodings, 0x15 (which encodes the "newline function", see the
          Unicode standard, chapter 5) maps to U+000A instead of U+0085.  This is
          for interoperability with C programs and Unix environments on z/OS.  */
-      #define ICONV_SURFACE_EBCDIC_ZOS_UNIX  1
+      constexpr int ICONV_SURFACE_EBCDIC_ZOS_UNIX = 1;////////////
 
       /* Requests for iconvctl. */
-      #define ICONV_TRIVIALP            0  /* int *argument */
-      #define ICONV_GET_DISCARD_ILSEQ   3  /* int *argument */
-      #define ICONV_SET_DISCARD_ILSEQ   4  /* const int *argument */
-      #define ICONV_SET_HOOKS           5  /* const struct iconv_hooks *argument */
-      #define ICONV_SET_FALLBACKS       6  /* const struct iconv_fallbacks *argument */
-      #define ICONV_GET_FROM_SURFACE    7  /* unsigned int *argument */
-      #define ICONV_SET_FROM_SURFACE    8  /* const unsigned int *argument */
-      #define ICONV_GET_TO_SURFACE      9  /* unsigned int *argument */
-      #define ICONV_SET_TO_SURFACE     10  /* const unsigned int *argument */
+      constexpr int  ICONV_TRIVIALP = 0;  /* int *argument */
+      constexpr int  ICONV_GET_DISCARD_ILSEQ = 3;  /* int *argument */
+      constexpr int  ICONV_SET_DISCARD_ILSEQ = 4;  /* const int *argument */
+      constexpr int  ICONV_SET_HOOKS = 5;  /* const struct iconv_hooks *argument */
+      constexpr int  ICONV_SET_FALLBACKS = 6;  /* const struct iconv_fallbacks *argument */
+      constexpr int  ICONV_GET_FROM_SURFACE = 7;  /* unsigned int *argument */
+      constexpr int  ICONV_SET_FROM_SURFACE = 8;  /* const unsigned int *argument */
+      constexpr int  ICONV_GET_TO_SURFACE = 9;  /* unsigned int *argument */
+      constexpr int  ICONV_SET_TO_SURFACE = 10;  /* const unsigned int *argument */
 
       /* Listing of locale independent encodings. */
       extern @DLL_VARIABLE@ void iconvlist (int (*do_one) (unsigned int namescount,