[stunnel-users] safestring and safename insecure

The macros safestring and safename in common.h are insecure if called for a character with high bit set, because (int)*p will sign-extend the byte on machines where char is signed. Possible patch (here for safestring; for safename correspondingly with isprint -> isalnum): do {char *p; for(p=(s); *p; p++) if(!isprint((int)*(unsigned char *)p)) *p='.';} while(0)