(Cherry-pick commit
17cfaaf from 'release-7_4' branch.)
docs are dist_doc_DATA. They should be installed to /usr/share/doc.
* doc/Makefile.am (dist_pkgdata_DATA): Remove COPYING, LICENSING.txt,
README.txt, README_stack.txt, README_malloc.txt, README_win32.txt.
* doc/Makefile.am (dist_doc_DATA): Add COPYING, LICENSING.txt,
README.txt, README_stack.txt, README_malloc.txt, README_win32.txt.
# installed documentation
#
-dist_pkgdata_DATA=COPYING LICENSING.txt README.txt README_stack.txt README_malloc.txt README_win32.txt
+dist_doc_DATA = COPYING LICENSING.txt README.txt README_stack.txt \
+ README_malloc.txt README_win32.txt