handle iconv() function that takes const char ** instead of char **

configure.in

@@ -33,12 +33,13 @@ AC_CHECK_HEADERS([dirent.h regex.h], , AC_MSG_ERROR(vital headers missing))
 dnl ======================
 dnl = checking for iconv =
 dnl ======================
-if test "$prefix" = "NONE"; then
-	encodings_file="${ac_default_prefix}"
-else
-	encodings_file="${prefix}"
-fi
-AC_CHECK_HEADERS([iconv.h], , AC_MSG_NOTICE(cannot find iconv.h header, iconv support will be disabled))
+AC_CHECK_HEADERS([iconv.h],
+	AC_MSG_CHECKING([whether iconv takes const char **])
+	AC_COMPILE_IFELSE(AC_LANG_PROGRAM([[#include <iconv.h>]], [[iconv(0, (const char **)0, 0, 0, 0);]]),
+		AC_MSG_RESULT([yes]) AC_DEFINE([ICONV_CONST], [const], [pass const pointer to iconv]),
+		AC_MSG_RESULT([no]) AC_DEFINE([ICONV_CONST], [], [pass non-const pointer to iconv]))
+	AC_CHECK_LIB(iconv, libiconv, LDFLAGS="$LDFLAGS -liconv", )
+, )
 
 dnl ========================
 dnl = checking for ncurses =

src/charset.cpp

@@ -73,7 +73,7 @@ namespace
 		char *outstart = outbuf;
 		char *instart = inbuf;
 		
-		if (iconv(cd, &inbuf, &len, &outbuf, &buflen) == (size_t)-1)
+		if (iconv(cd, const_cast<ICONV_CONST char **>(&inbuf), &len, &outbuf, &buflen) == (size_t)-1)
 		{
 			delete [] outstart;
 			iconv_close(cd);