Sometimes 'char' is not enough. C doesn't specify if it is
signed or unsigned. Here we had to explicitly use 'signed char'
instead of 'char'.
Gcc can be switched to unsigned char with -funsigned-char.
Reported-by: Michael <michael@cyber-dome.com>
* include/wget/wget.h: Remove G_GNUC_WGET_NONNULL from several functions
* libwget/buffer.c: Add explicit checks for NULL
* libwget/buffer_printf.c (wget_buffer_vprintf_append): Likewise
* libwget/net.c: Likewise
The nonnull attribute removes the NULL checks under certain conditions.
That might turn out as a security flaw.
Removed wget_buffer_vprintf_append, wget_buffer_printf_append,
wget_buffer_vprintf2 and wget_buffer_printf2.
Renamed their *2 counterpart to their old names.
