[newlib-cygwin] libc: fix fropen/fwopen compile warnings

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=0b09753a3f0c17164c877cf5ae9ebbc617bcf302

commit 0b09753a3f0c17164c877cf5ae9ebbc617bcf302
Author:     Alexey Lapshin <alexey.lapshin@espressif.com>
AuthorDate: Wed Dec 7 10:59:23 2022 +0000
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Dec 7 13:10:24 2022 +0100

    libc: fix fropen/fwopen compile warnings
    
    This patch fixes warnings that appears when compiling:
    
    #define fwopen(__cookie,__fn) funopen(__cookie, (int (*)())0, __fn,
    (fpos_t (*)())0, (int (*)())0)
    Expands to:
    
    funopen(__null, (int (*)())0, &app_printf, (fpos_t (*)())0, (int
    (*)())0)
    argument of type "int (*)()" is incompatible with parameter of type
    "int (*)(void *__cookie, char *__buf, int __n)"C/C++(167)
    invalid conversion from 'fpos_t (*)()' {aka 'long int (*)()'} to
    'fpos_t (*)(void*, fpos_t, int)' {aka 'long int (*)(void*,
    
    Discussion is here:
    https://github.com/espressif/arduino-esp32/issues/7407

Diff:
---
 newlib/libc/include/stdio.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/newlib/libc/include/stdio.h b/newlib/libc/include/stdio.h
index ea4ddf3293d0..77966578d802 100644
--- a/newlib/libc/include/stdio.h
+++ b/newlib/libc/include/stdio.h
@@ -620,10 +620,8 @@ FILE	*_funopen_r (struct _reent *, const void *__cookie,
 		int (*__closefn)(void *__cookie));
 # endif /* !__LARGE64_FILES */
 
-# define	fropen(__cookie, __fn) funopen(__cookie, __fn, (int (*)())0, \
-					       (fpos_t (*)())0, (int (*)())0)
-# define	fwopen(__cookie, __fn) funopen(__cookie, (int (*)())0, __fn, \
-					       (fpos_t (*)())0, (int (*)())0)
+# define	fropen(__cookie, __fn) funopen(__cookie, __fn, NULL, NULL, NULL)
+# define	fwopen(__cookie, __fn) funopen(__cookie, NULL, __fn, NULL, NULL)
 #endif /* __BSD_VISIBLE */
 
 #if __GNU_VISIBLE