zdev: Implement internal device attributes

This change adds base infrastructure for implementing internal device
attributes. In the context of the zdev tools, an internal device
attribute is a new type of device attribute with the following
characteristics:

  - Can be set and removed like normal device attributes
  - Affects zdev-internal handling only
  - Does not correspond to an actual device attribute, that is
    it has no representation in SysFS
  - Can not be set in the active configuration
  - Name starts with "zdev:" to prevent conflicts with actual
    device attributes

Values for internal device attributes are stored in udev rules alongside
the normal persistent configuration of a device. They are encoded as
udev environment variables. Note that they have no further effect on
udev processing.

Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/src/Makefile

@@ -8,7 +8,7 @@ ALL_CPPFLAGS += -I ../include -std=gnu99 -Wno-unused-parameter \
 chzdev_objects += attrib.o chzdev.o device.o devnode.o devtype.o exit_code.o \
 		  export.o hash.o inuse.o misc.o namespace.o opts.o path.o \
 		  root.o select.o setting.o subtype.o table.o table_attribs.o \
-		  table_types.o net.o firmware.o
+		  table_types.o net.o firmware.o internal.o
 
 # Devtype Helpers
 chzdev_objects += blkinfo.o ccw.o ccwgroup.o findmnt.o modprobe.o module.o \
@@ -38,7 +38,7 @@ chzdev_objects += generic_ccw.o
 lszdev_objects += attrib.o lszdev.o device.o devnode.o devtype.o exit_code.o \
 		  export.o hash.o inuse.o misc.o namespace.o opts.o path.o \
 		  root.o select.o setting.o subtype.o table.o table_types.o \
-		  net.o
+		  net.o internal.o
 
 # Devtype Helpers
 lszdev_objects += blkinfo.o ccw.o ccwgroup.o findmnt.o modprobe.o module.o \