ssh: Run keygen on post-install

extra/openssh/checksums

@@ -1,2 +1,2 @@
 43925151e6cf6cee1450190c0e9af4dc36b41c12737619edff8bcebdff64e671  openssh-8.2p1.tar.gz
-5d32a817344ac444424063d75e49afd95d7eb76d972ef5c5cfad355c8e8b1ff1  sshd.run
+cd9a79943f8f6c05373bd70afc22a230f3c5e6e6200b9115f598e180dacefb54  sshd.run

extra/openssh/files/sshd.run

@@ -1,3 +1,2 @@
 #!/bin/sh
-ssh-keygen -A >/dev/null 2>&1 # Will generate host keys if they don't already exist.
 exec /usr/bin/sshd -D

extra/openssh/post-install

@@ -0,0 +1,3 @@
+#!/bin/sh
+# Generate host keys if they don't already exist.
+ssh-keygen -A >/dev/null 2>&1