tree-wide: use -EBADF for fd initialization

-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.

Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state

Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.

In some places, initialization is dropped if unnecessary.

coccinelle/safe_close.cocci

@@ -3,17 +3,17 @@
 expression fd;
 @@
 - close(fd);
-- fd = -1;
+- fd = -EBADF;
 + fd = safe_close(fd);
 @@
 expression fd;
 @@
 - close_nointr(fd);
-- fd = -1;
+- fd = -EBADF;
 + fd = safe_close(fd);
 @@
 expression fd;
 @@
 - safe_close(fd);
-- fd = -1;
+- fd = -EBADF;
 + fd = safe_close(fd);