macro: introduce new TAKE_FD() macro

This is similar to TAKE_PTR() but operates on file descriptors, and thus
assigns -1 to the fd parameter after returning it.

Removes 60 lines from our codebase. Pretty good too I think.

src/basic/memfd-util.c

@@ -168,8 +168,5 @@ int memfd_new_and_map(const char *name, size_t sz, void **p) {
         if (r < 0)
                 return r;
 
-        r = fd;
-        fd = -1;
-
-        return r;
+        return TAKE_FD(fd);
 }