Fix an operator precedence problem on the [1d8086902e] check-in.

FossilOrigin-Name: 4f5f3aebe81c3cbe539db3e33ec38fa3de47e90b

src/os_unix.c

@@ -554,7 +554,7 @@ static int robust_open(const char *z, int f, mode_t m){
       struct stat statbuf;
       if( osFstat(fd, &statbuf)==0 
        && statbuf.st_size==0
-       && statbuf.st_mode&0777!=m 
+       && (statbuf.st_mode&0777)!=m 
       ){
         osFchmod(fd, m);
       }