Revert "nss: prevent PROTECT_ERRNO from squashing changes to *errnop"

This reverts commit b26c904113.

I don't see anythign wrong, but Ubuntu autopkgtest CI started failing fairly
consistently since this was merged. Let's see if reverting fixes things.

src/basic/util.h

@@ -174,33 +174,12 @@ static inline void *mempset(void *s, int c, size_t n) {
 }
 
 static inline void _reset_errno_(int *saved_errno) {
-        if (*saved_errno >= 0)
-                errno = *saved_errno;
+        errno = *saved_errno;
 }
 
 #define PROTECT_ERRNO                                                   \
         _cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno
 
-/*
- * NSS modules should indicate errors by assigning to the passed-in *errnop
- * rather than errno directly; however in dynamically-linked programs, errnop
- * == &errno, so PROTECT_ERRNO has to be disabled in order for assigning to
- * *errnop to be effective.
- */
-#define DISARM_PROTECT_ERRNO(r) \
-        ({ \
-                _reset_errno_(&_saved_errno_); \
-                _saved_errno_ = -1; \
-                abs(r); \
-        })
-
-#define DISARM_PROTECT_ERRNO_INNER(r) \
-        ({ \
-                _reset_errno_(_saved_errno_p); \
-                *_saved_errno_p = -1; \
-                abs(r); \
-        })
-
 static inline int negative_errno(void) {
         /* This helper should be used to shut up gcc if you know 'errno' is
          * negative. Instead of "return -errno;", use "return negative_errno();"