C89isms in the test suite

[Florian Weimer]

* Sam James:

> Would you be able to backport 6be2672e4ee41c566a9e072088cccca263bab5f7
> and 885b6660c17fb91980b5682514ef54668e544b02 to the active <13
> branches?

Jakub, okay to backport these two (to 12, 11, 10 I presume)?

commit 6be2672e4ee41c566a9e072088cccca263bab5f7
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Oct 18 16:58:48 2022 +0200

    libsanitizer: Avoid implicit function declaration in configure test
    
    libsanitizer/
    
            * configure.ac (sanitizer_supported): Include <unistd.h> for
            syscall prototype.
            * configure: Regenerate.

commit 885b6660c17fb91980b5682514ef54668e544b02
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Oct 18 16:58:48 2022 +0200

    libiberty: Fix C89-isms in configure tests
    
    libiberty/
    
            * acinclude.m4 (ac_cv_func_strncmp_works): Add missing
            int return type and parameter list to the definition of main.
            Include <stdlib.h> and <string.h> for prototypes.
            (ac_cv_c_stack_direction): Add missing
            int return type and parameter list to the definitions of
            main, find_stack_direction.  Include <stdlib.h> for exit
            prototype.
            * configure: Regenerate.

Thanks,
Florian