image.bbclass: also mask debugfs versions of masked images

When IMAGE_GEN_DEBUGFS is enabled, and IMAGE_FSTYPES_DEBUGFS is left
at its default (as suggested by local.conf.sample.extended),
recipe parsing fails:

  bitbake kern-tools-native # or anything else for that matter
  ERROR: <poky.git>/meta/recipes-core/images/build-appliance-image_15.0.0.bb: No IMAGE_CMD defined for IMAGE_FSTYPES entry 'debugfs_vmdk' - possibly invalid type name or missing support class
  ERROR: Failed to parse recipe: <poky.git>/meta/recipes-core/images/build-appliance-image_15.0.0.bb

  Summary: There was 1 WARNING message shown.
  Summary: There were 2 ERROR messages shown, returning a non-zero exit code.

i.e. bitbake doesn't even finish parsing...

Since IMAGE_FSTYPES_DEBUGFS is based on IMAGE_FSTYPES, and
since the build-appliance-image is setting IMAGE_FSTYPES
to vmdk, image.bbclass/image_types.bbclass will be trying
to build a debugfs_vmdk, causing the error, as this is not
implemented.

One solution to solving this problem could be as simple as
adding a line
  IMAGE_FSTYPES_DEBUGFS_remove = "vmdk"
to the build-appliance-image recipe, but that is very
specific to the error encountered and carries the risk of
the error being reintroduced in another recipe.

Another solution could be to add 'debugfs_vmdk' to
IMAGE_TYPES_MASKED in image-vm.bbclass, but again, this
approach doesn't seem generic enough.

None of the live and vm type images have an implementation
for building a debugfs version, it doesn't seem to make
sense to build debugfs versions of any of them anyway, and
given IMAGE_TYPES_MASKED appears to be intended for those
image types exclusively, it seems the right approach is to
unconditionally also mask all debugfs_ flavours from
IMAGE_TYPES_MASKED to achieve a generic solution.

Do that so.

(From OE-Core rev: 9bd682c4f1c19d68c573c11822888ee799809272)

Signed-off-by: André Draszik <git@andred.net>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/image.bbclass

@@ -415,6 +415,7 @@ python () {
     d.appendVarFlag('do_image', 'vardeps', ' '.join(vardeps))
 
     maskedtypes = (d.getVar('IMAGE_TYPES_MASKED', True) or "").split()
+    maskedtypes = [dbg + t for t in maskedtypes for dbg in ("", "debugfs_")]
 
     for t in basetypes:
         vardeps = set()