make html: Exclude mkapiref.py from source list
@@ -42,7 +42,7 @@ apiref: mkapiref.py \
$(top_srcdir)/lib/includes/ngtcp2/ngtcp2.h
$(top_srcdir)/doc/mkapiref.py \
source/apiref.rst source/macros.rst source/enums.rst source/types.rst \
- source $^
+ source $(wordlist 2, $(words $^), $^)
html-local: apiref
@$(SPHINXBUILD) -M html "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
