asciidoc: set CLEANBROKEN to fix rebuild

The following changes since commit 5ac0604fdc7d5b783011c43d476210b427b5dae0:

build-appliance-image: Create image in correct location (2016-09-19 08:58:04 +0100)

are available in the git repository at:

git://git.openembedded.org/openembedded-core-contrib rbt/ascii
http://cgit.openembedded.org/cgit.cgi/openembedded-core-contrib/log/?h=rbt/ascii

Robert Yang (1):
asciidoc: set CLEANBROKEN to fix rebuild

 meta/recipes-extended/asciidoc/asciidoc_8.6.9.bb | 2 ++
 1 file changed, 2 insertions(+)

2.9.0

The make clean removes doc/a2x.1 and doc/asciidoc.1, then it would cause
build failures since in the second build:
Fixing CONF_DIR in asciidoc.py
Fixing CONF_DIR in a2x.py
python a2x.py -f manpage doc/a2x.1.txt
a2x: ERROR: "xmllint" --nonet --noout --valid "/path/to/asciidoc-native/8.6.9-r0/asciidoc-8.6.9/doc/a2x.1.xml" returned non-zero exit status 4
make: *** [doc/a2x.1] Error 1

The xmllint failed because "--nonext" is used:
I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd
/buildarea/lyang1/test_arm/tmp/work/x86_64-linux/asciidoc-native/8.6.9-r0/asciidoc-8.6.9/doc/a2x.1.xml:2: warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"

Avoid running make clean will fix the problem.

---
 meta/recipes-extended/asciidoc/asciidoc_8.6.9.bb | 2 ++
 1 file changed, 2 insertions(+)

index 2091eec..1cd1454 100644
@@ -20,3 +20,5 @@ export DESTDIR = "${D}"
 DEPENDS_class-native = "docbook-xml-dtd4-native"
 RDEPENDS_${PN} += "python" 
 BBCLASSEXTEND = "native"
+
+CLEANBROKEN = "1"

2.9.0