striconveha: Improve GCC 11 allocation-deallocation checking

[Bruno Haible]

2021-08-07  Bruno Haible  <bruno@clisp.org>

        striconveha: Improve GCC 11 allocation-deallocation checking.
        * lib/striconveha.h: Include <stdlib.h> instead of <stddef.h>.
        (str_iconveha): Declare that deallocation must happen through 'free'.

diff --git a/lib/striconveha.h b/lib/striconveha.h
index baa50f5..5c47a44 100644
--- a/lib/striconveha.h
+++ b/lib/striconveha.h
@@ -19,7 +19,7 @@
 #define _STRICONVEHA_H
 
 #include <stdbool.h>
-#include <stddef.h>
+#include <stdlib.h>
 
 #include "iconveh.h"
 
@@ -69,7 +69,8 @@ extern char *
        str_iconveha (const char *src,
                      const char *from_codeset, const char *to_codeset,
                      bool transliterate,
-                     enum iconv_ilseq_handler handler);
+                     enum iconv_ilseq_handler handler)
+       _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE;
 
 
 /* In the above, FROM_CODESET can also be one of the following values: