Merge branch '409-autoconf-2.70-causes-resulting-configure-file-to-fail' into 'master'

Drop use of obsoleted autoconf AC_HEADER_STDC macro.  Fixes #409

Closes #409

See merge request sane-project/backends!566

acinclude.m4

@@ -73,9 +73,6 @@ AC_DEFUN([SANE_CHECK_MISSING_HEADERS],
   if test "${ac_cv_header_unistd_h}" != "yes" ; then
     MISSING_HEADERS="${MISSING_HEADERS}\"unistd.h\" "
   fi
-  if test "${ac_cv_header_stdc}" != "yes" ; then
-    MISSING_HEADERS="${MISSING_HEADERS}\"ANSI C headers\" "
-  fi
   if test "${MISSING_HEADERS}" != "" ; then
     echo "*** The following essential header files couldn't be found:"
     echo "*** ${MISSING_HEADERS}"

lib/md5.c

@@ -26,14 +26,8 @@
 
 #include <sys/types.h>
 
-#if STDC_HEADERS || defined _LIBC
-# include <stdlib.h>
-# include <string.h>
-#else
-# ifndef HAVE_MEMCPY
-#  define memcpy(d, s, n) bcopy ((s), (d), (n))
-# endif
-#endif
+#include <stdlib.h>
+#include <string.h>
 
 #include "md5.h"
 

sanei/sanei_pa4s2.c

@@ -150,11 +150,9 @@ static int sanei_pa4s2_dbg_init_called = SANE_FALSE;
 
 #endif /* NDEBUG */
 
-#if defined(STDC_HEADERS)
-# include <errno.h>
-# include <stdio.h>
-# include <stdlib.h>
-#endif
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #if defined(HAVE_STRING_H)
 # include <string.h>
 #elif defined(HAVE_STRINGS_H)

sanei/sanei_pp.c

@@ -135,11 +135,9 @@ inb( u_long port )
 #include "../include/sane/sanei_debug.h"
 #include "../include/sane/sanei_pp.h"
 
-#if defined(STDC_HEADERS)
-# include <errno.h>
-# include <stdio.h>
-# include <stdlib.h>
-#endif
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #if defined(HAVE_STRING_H)
 # include <string.h>
 #elif defined(HAVE_STRINGS_H)