Remove HAVE_ERRNO_H from libgd

The check for errno.h has been removed via
50b9ef8

Upstream libgd library is also patched via
libgd/libgd@1e7f939

Author: petk

ext/gd/libgd/gdkanji.c

@@ -11,10 +11,8 @@
 #include <stdarg.h>
 #if defined(HAVE_ICONV_H) || defined(HAVE_ICONV)
 #include <iconv.h>
-#ifdef HAVE_ERRNO_H
 #include <errno.h>
 #endif
-#endif
 
 #if defined(HAVE_ICONV_H) && !defined(HAVE_ICONV)
 #define HAVE_ICONV 1
@@ -349,11 +347,9 @@ do_convert (unsigned char *to, unsigned char *from, const char *code)
   if ((cd = iconv_open (EUCSTR, code)) == (iconv_t) - 1)
     {
       error ("iconv_open() error");
-#ifdef HAVE_ERRNO_H
       if (errno == EINVAL)
 	error ("invalid code specification: \"%s\" or \"%s\"",
 	       EUCSTR, code);
-#endif
       strcpy ((char *) to, (const char *) from);
       return;
     }
@@ -363,15 +359,13 @@ do_convert (unsigned char *to, unsigned char *from, const char *code)
 
   if ((int) iconv(cd, (char **) &from, &from_len, (char **) &to, &to_len) == -1)
     {
-#ifdef HAVE_ERRNO_H
       if (errno == EINVAL)
 	error ("invalid end of input string");
       else if (errno == EILSEQ)
 	error ("invalid code in input string");
       else if (errno == E2BIG)
 	error ("output buffer overflow at do_convert()");
       else
-#endif
 	error ("something happen");
       strcpy ((char *) to, (const char *) from);
       return;