remove build warning about 'fdopen'

remove build warning about 'fdopen'

zlib-ng/test/fuzz/minigzip_fuzzer.c:153:31: warning: implicit declaration of function 'fdopen' is invalid in C99 [-Wimplicit-function-declaration]
    gz->file = path == NULL ? fdopen(fd, gz->write ? "wb" : "rb") :
                              ^
zlib-ng/test/fuzz/minigzip_fuzzer.c:153:29: warning: pointer/integer type mismatch in conditional expression ('int' and 'FILE *' (aka 'struct _IO_FILE *'))
      [-Wconditional-type-mismatch]
    gz->file = path == NULL ? fdopen(fd, gz->write ? "wb" : "rb") :
                            ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~