ctags: set CLEANBROKEN

Tries to call sphinx-build during clean in docs directory and fails when
not installed on host nor included in HOSTTOOLS

Fixes do_configure failure when re-executed in existing WORKDIR

...
rm -f ./*.gcov
make[2]: Entering directory '/OE/tmp/work/x86_64-linux/ctags-native/6.2.20261011.0/sources/ctags-6.2.20261011.0/docs'
/bin/sh: 1: sphinx-build: not found
make[2]: Leaving directory '/OE/tmp/work/x86_64-linux/ctags-native/6.2.20261011.0/sources/ctags-6.2.20261011.0/docs'
make[2]: *** [Makefile:20: clean] Error 127
make[1]: *** [Makefile:8218: clean-local] Error 2
make[1]: Leaving directory '/OE/tmp/work/x86_64-linux/ctags-native/6.2.20261011.0/sources/ctags-6.2.20261011.0'
make: *** [Makefile:7175: clean-recursive] Error 1
ERROR: oe_runmake failed
WARNING: exit code 1 from a shell command.

The issue was introduced in p6.2.20260802.0 version with:
https://github.com/universal-ctags/ctags/commit/05a8061a581f626deada11da5300822bee20e458
which replaced "rm -rf $(BUILDDIR) $(EXTDIR)/__pycache__" in clean with
sphinx-build clean:
@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

Signed-off-by: Martin Jansa <martin.jansa@gmail.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-oe/recipes-devtools/ctags/ctags_6.2.20261101.0.bb

@@ -33,3 +33,6 @@ PACKAGECONFIG[yaml] = "--enable-yaml,--disable-yaml,libyaml"
 PACKAGECONFIG[manpages] = ",,python3-docutils-native"
 
 BBCLASSEXTEND = "native"
+
+# calls sphinx-build during clean
+CLEANBROKEN = "1"