procd: include hotplug rule fragments from drop-in dirs

The hotplug rules live in a single /etc/hotplug.json, so a package
that needs a device node named, owned or grouped its own way has no
way to contribute one; the alternatives are patching the shared file
or falling back to a shell script under /etc/hotplug.d.

Load /etc/hotplug.json.d/*.json from inside the device node branch,
ahead of the built-in name rules, and /etc/hotplug-preinit.json.d/*
at the end of the preinit script. Fragments are run in sorted order.
A fragment that creates a node keeps it: the generic rule below still
runs, but its mknod() fails with EEXIST and leaves the node alone.

This is done in preparation for deprecating some of the subtarget-wide
FEATURES flags, instead introducing feature-umbrella packages such as
`video-support` and `audio-support` shipping the hotplug rule snippets
and having all providers (ie. kmods) and users depend on them.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/system/procd/Makefile

@@ -12,9 +12,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(PROJECT_GIT)/project/procd.git
-PKG_MIRROR_HASH:=b193107814e7b378fcbe519749aa1d92994f6d1cbc0c25faf0833f6b46811785
-PKG_SOURCE_DATE:=2026-09-26
-PKG_SOURCE_VERSION:=a6f9ffd4becffac99adf7368b26dde537c721f6f
+PKG_MIRROR_HASH:=6d336595493088058966b790837db75c5f9aa8cf8dd9151e2d1d554152f19891
+PKG_SOURCE_DATE:=2026-09-27
+PKG_SOURCE_VERSION:=675942be0e25fd4a4abb030820de432c1dd37a0a
 CMAKE_INSTALL:=1
 
 PKG_LICENSE:=GPL-2.0
@@ -113,7 +113,8 @@ SECCOMP=$(if $(CONFIG_PACKAGE_procd-seccomp),1,0)
 CMAKE_OPTIONS += -DSECCOMP_SUPPORT=$(SECCOMP) -DUTRACE_SUPPORT=$(SECCOMP)
 
 define Package/procd/install
-	$(INSTALL_DIR) $(1)/sbin $(1)/etc $(1)/lib/functions
+	$(INSTALL_DIR) $(1)/sbin $(1)/etc $(1)/etc/hotplug.json.d \
+		$(1)/etc/hotplug-preinit.json.d $(1)/lib/functions
 
 	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/sbin/{init,procd,askfirst,udevtrigger,upgraded} $(1)/sbin/
 	$(INSTALL_DATA) $(PKG_INSTALL_DIR)/usr/lib/libsetlbf.so $(1)/lib

package/system/procd/files/hotplug-preinit.json

@@ -14,5 +14,6 @@
 	[ "if",
 		[ "eq", "SUBSYSTEM", "button" ],
 		[ "exec", "/etc/rc.button/failsafe" ]
-	]
+	],
+	[ "include", "/etc/hotplug-preinit.json.d/*.json" ]
 ]

package/system/procd/files/hotplug.json

@@ -27,6 +27,7 @@
 							[ "return" ]
 						]
 					],
+					[ "include", "/etc/hotplug.json.d/*.json" ],
 					[ "if",
 						[ "regex", "DEVNAME", "^snd" ],
 						[ "makedev", "/dev/%DEVNAME%", "0660", "audio" ]