Drop useradd's backwards-compatibility -O flag

No users appear left in Debian.

debian/patches/series

@@ -5,4 +5,3 @@ Set-group-and-mode-for-g-shadow-files.patch
 Keep-using-Debian-adduser-defaults.patch
 Document-the-shadowconfig-utility.patch
 Recommend-using-adduser-and-deluser.patch
-useradd-accept-the-O-flag-for-backward-compatibility.patch

debian/patches/useradd-accept-the-O-flag-for-backward-compatibility.patch

@@ -1,52 +0,0 @@
-From: Shadow package maintainers <pkg-shadow-devel@lists.alioth.debian.org>
-Date: Sat, 22 Jun 2024 17:39:41 +0200
-Subject: useradd: accept the -O flag for backward compatibility
-
-Note: useradd.8 needs to be regenerated.
-
-Status wrt upstream: not included as this is just specific
-                     backward compatibility for Debian
-
-Gbp-Topic: debian
----
- man/useradd.8.xml | 5 +++++
- src/useradd.c     | 3 ++-
- 2 files changed, 7 insertions(+), 1 deletion(-)
-
-diff --git a/man/useradd.8.xml b/man/useradd.8.xml
-index c98b214..20618bc 100644
---- a/man/useradd.8.xml
-+++ b/man/useradd.8.xml
-@@ -333,6 +333,11 @@
- 	    =<replaceable>100</replaceable>&nbsp;<option>-K</option>&nbsp;
- 	    <replaceable>UID_MAX</replaceable>=<replaceable>499</replaceable>
- 	  </para>
-+          <para>
-+            For the compatibility with previous Debian's
-+            <command>useradd</command>, the <option>-O</option> option is
-+            also supported.
-+          </para>
- 	  <!--para>
- 	    Note: <option>-K</option>&nbsp;<replaceable>UID_MIN</replaceable>=<replaceable>10</replaceable>,<replaceable>UID_MAX</replaceable>=<replaceable>499</replaceable>
- 	    doesn't work yet.
-diff --git a/src/useradd.c b/src/useradd.c
-index ac43edd..1cf3349 100644
---- a/src/useradd.c
-+++ b/src/useradd.c
-@@ -1215,7 +1215,7 @@ static void process_flags (int argc, char **argv)
- 			{NULL, 0, NULL, '\0'}
- 		};
- 		while ((c = getopt_long (argc, argv,
--					 "b:c:d:De:f:g:G:hk:K:lmMNop:rR:P:s:u:U"
-+					 "b:c:d:De:f:g:G:hk:O:K:lmMNop:rR:P:s:u:U"
- #ifdef WITH_SELINUX
- 		                         "Z:"
- #endif				/* WITH_SELINUX */
-@@ -1355,6 +1355,7 @@ static void process_flags (int argc, char **argv)
- 				kflg = true;
- 				break;
- 			case 'K':
-+			case 'O': /* compatibility with previous Debian useradd */
- 				/*
- 				 * override login.defs defaults (-K name=value)
- 				 * example: -K UID_MIN=100 -K UID_MAX=499