xmlrpc: compiler warnings in trunk and 5.1

[ovidiusas]

CentOS Linux release 7.4.1708 (Core)

CC (gcc) [M xmlrpc.so]          xmlrpc.o
xmlrpc.c: In function 'set_fault':
xmlrpc.c:894:2: warning: implicit declaration of function 'vsnprintf' [-Wimplicit-function-declaration]
  vsnprintf(buf, REASON_BUF_LEN, fmt, ap);
  ^
xmlrpc.c: In function 'print_value':
xmlrpc.c:1024:4: warning: implicit declaration of function 'snprintf' [-Wimplicit-function-declaration]
    body.len = snprintf(buf, 256, "%f", va_arg(*ap, double));
    ^
xmlrpc.c:1024:15: warning: incompatible implicit declaration of built-in function 'snprintf' [enabled by default]
    body.len = snprintf(buf, 256, "%f", va_arg(*ap, double));
               ^

[miconda]

Thanks, reopen if still an issue.