Don't redefine errno(3)

It is Undefined Behavior to declare errno (see NOTES in its manual page).
Instead of using the errno dummy declaration, use one that doesn't need
a comment.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

libmisc/addgrps.c

@@ -109,6 +109,6 @@ int add_groups (const char *list)
 	return 0;
 }
 #else				/* HAVE_SETGROUPS && !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* HAVE_SETGROUPS && !USE_PAM */
 

libmisc/audit_help.c

@@ -82,6 +82,6 @@ void audit_logger_message (const char *message, shadow_audit_result result)
 }
 
 #else				/* WITH_AUDIT */
-extern int errno;	/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* WITH_AUDIT */
 

libmisc/find_new_sub_gids.c

@@ -59,6 +59,6 @@ int find_new_sub_gids (gid_t *range_start, unsigned long *range_count)
 	return 0;
 }
 #else				/* !ENABLE_SUBIDS */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !ENABLE_SUBIDS */
 

libmisc/find_new_sub_uids.c

@@ -59,6 +59,6 @@ int find_new_sub_uids (uid_t *range_start, unsigned long *range_count)
 	return 0;
 }
 #else				/* !ENABLE_SUBIDS */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !ENABLE_SUBIDS */
 

libmisc/limits.c

@@ -550,6 +550,6 @@ void setup_limits (const struct passwd *info)
 }
 
 #else				/* !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */
 

libmisc/obscure.c

@@ -302,5 +302,5 @@ bool obscure (const char *old, const char *new, const struct passwd *pwdp)
 }
 
 #else				/* !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */

libmisc/pam_pass.c

@@ -55,5 +55,5 @@ void do_pam_passwd (const char *user, bool silent, bool change_expired)
 	(void) pam_end (pamh, PAM_SUCCESS);
 }
 #else				/* !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */

libmisc/pam_pass_non_interactive.c

@@ -141,5 +141,5 @@ int do_pam_passwd_non_interactive (const char *pam_service,
 	return ((PAM_SUCCESS == ret) ? 0 : 1);
 }
 #else				/* !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */

libmisc/pwd2spwd.c

@@ -62,6 +62,6 @@ struct spwd *pwd_to_spwd (const struct passwd *pw)
 	return &sp;
 }
 #else				/* USE_PAM */
-extern int errno;	/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */
 

libmisc/pwdcheck.c

@@ -34,5 +34,5 @@ void passwd_check (const char *user, const char *passwd, unused const char *prog
 	}
 }
 #else			/* USE_PAM */
-extern int errno;	/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif			/* USE_PAM */

libmisc/tz.c

@@ -52,6 +52,6 @@
 	return tzbuf;
 }
 #else				/* !USE_PAM */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !USE_PAM */