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>

lib/gshadow.c

@@ -502,5 +502,5 @@ int putsgent (const struct sgrp *sgrp, FILE * fp)
 	return 0;
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/*} SHADOWGRP */

lib/lockpw.c

@@ -81,5 +81,5 @@ int ulckpwdf (void)
 	return (pw_unlock () && spw_unlock ())? 0 : -1;
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif

lib/nscd.c

@@ -53,6 +53,6 @@ int nscd_flush_cache (const char *service)
 	return 0;
 }
 #else				/* USE_NSCD */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* USE_NSCD */
 

lib/pwauth.c

@@ -207,5 +207,5 @@ int pw_auth (const char *cipher,
 	return retval;
 }
 #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 */

lib/selinux.c

@@ -206,5 +206,5 @@ int check_selinux_permit (const char *perm_name)
 }
 
 #else				/* !WITH_SELINUX */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !WITH_SELINUX */

lib/semanage.c

@@ -357,5 +357,5 @@ done:
 	return ret;
 }
 #else				/* !WITH_SELINUX */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* !WITH_SELINUX */

lib/sgetspent.c

@@ -182,6 +182,6 @@ struct spwd *sgetspent (const char *string)
 	return (&spwd);
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif
 

lib/sgroupio.c

@@ -302,5 +302,5 @@ int sgr_sort ()
 	return commonio_sort_wrt (&gshadow_db, __gr_get_db ());
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif

lib/shadow.c

@@ -525,6 +525,6 @@ struct spwd *getspnam (const char *name)
 	return (sp);
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif
 

lib/sssd.c

@@ -70,6 +70,6 @@ int sssd_flush_cache (int dbflags)
 	return 0;
 }
 #else				/* USE_SSSD */
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif				/* USE_SSSD */
 

lib/subordinateio.c

@@ -1097,6 +1097,6 @@ bool release_subid_range(struct subordinate_range *range, enum subid_type id_typ
 }
 
 #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 */
 

lib/utent.c

@@ -66,5 +66,5 @@ struct utmp *getutent (void)
 	return &utmp_buf;
 }
 #else
-extern int errno;		/* warning: ANSI C forbids an empty source file */
+extern int ISO_C_forbids_an_empty_translation_unit;
 #endif