tree-wide: some work-arounds for gcc false positives regarding uninitialized variables

src/basic/process-util.c

@@ -553,7 +553,7 @@ int wait_for_terminate(pid_t pid, siginfo_t *status) {
                         if (errno == EINTR)
                                 continue;
 
-                        return -errno;
+                        return negative_errno();
                 }
 
                 return 0;

src/journal/mmap-cache.c

@@ -481,7 +481,7 @@ static int mmap_try_harder(MMapCache *m, void *addr, int fd, int prot, int flags
                 if (ptr != MAP_FAILED)
                         break;
                 if (errno != ENOMEM)
-                        return -errno;
+                        return negative_errno();
 
                 r = make_room(m);
                 if (r < 0)
@@ -571,7 +571,7 @@ static int add_mmap(
         return 1;
 
 outofmem:
-        munmap(d, wsize);
+        (void) munmap(d, wsize);
         return -ENOMEM;
 }
 

src/network/networkd-brvlan.c

@@ -58,7 +58,7 @@ static int append_vlan_info_data(Link *const link, sd_netlink_message *req, uint
         struct bridge_vlan_info br_vlan;
         int i, j, k, r, done, cnt;
         uint16_t begin, end;
-        bool untagged;
+        bool untagged = false;
 
         assert(link);
         assert(req);