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/fd-util.h

@@ -105,3 +105,11 @@ int rearrange_stdio(int original_input_fd, int original_output_fd, int original_
 static inline int make_null_stdio(void) {
         return rearrange_stdio(-1, -1, -1);
 }
+
+/* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
+#define TAKE_FD(fd)                             \
+        ({                                      \
+                int _fd_ = (fd);                \
+                (fd) = -1;                      \
+                _fd_;                           \
+        })