tree-wide: code improvements suggested by Coccinelle

src/shared/dns-domain.c

@@ -37,7 +37,7 @@ int dns_label_unescape(const char **name, char *dest, size_t sz, DNSLabelFlags f
         d = dest;
 
         for (;;) {
-                if (*n == 0 || *n == '.') {
+                if (IN_SET(*n, 0, '.')) {
                         if (FLAGS_SET(flags, DNS_LABEL_LDH) && last_char == '-')
                                 /* Trailing dash */
                                 return -EINVAL;

src/shared/machine-image.c

@@ -395,7 +395,7 @@ static int image_make(
                 if (r < 0)
                         return r;
 
-                if (size != 0 && size != UINT64_MAX)
+                if (!IN_SET(size, 0, UINT64_MAX))
                         (*ret)->usage = (*ret)->usage_exclusive = (*ret)->limit = (*ret)->limit_exclusive = size;
 
                 return 0;