build: Simplify: Don't build libintl+libgnuintl a second time in gettext-tools.
* PACKAGING: Document that gettext-tools cannot be built without
gettext-runtime.
* autogen.sh: Don't create gettext-tools/intl/Makefile.am.
* gettext-tools/Makefile.am (SUBDIRS): Remove 'intl'.
* gettext-runtime/intl/Makefile.am (dist-hook): Remove.
(install-data-local, uninstall-local, uninstall-sources): Moved ...
* gettext-tools/misc/Makefile.am (install-data-local, uninstall-local,
uninstall-sources): ... to here.
* gettext-runtime/configure.ac (PACKAGE_IS_GETTEXT_TOOLS): Remove conditional.
* gettext-tools/configure.ac: Add 3rd argument to AM_GNU_GETTEXT invocation.
(PACKAGE_IS_GETTEXT_TOOLS): Remove conditional.
Update reference to os2compat.h.
Don't create intl/Makefile from intl/Makefile.in.
* gettext-tools/gnulib-lib/Makefile.am (AM_CPPFLAGS): Use the built header files
in gettext-runtime/intl/.
* gettext-tools/libgrep/Makefile.am (AM_CPPFLAGS): Likewise.
* gettext-tools/src/Makefile.am (AM_CPPFLAGS): Likewise.
* gettext-tools/libgettextpo/Makefile.am (AM_CPPFLAGS): Likewise.
* gettext-tools/gnulib-tests/Makefile.am (AM_CPPFLAGS): Likewise.
* gettext-tools/tests/Makefile.am (AM_CPPFLAGS): Likewise.
(LDADD_yes, LDADD_no): Use the built libraries in gettext-runtime/intl/.
* gettext-tools/tests/lang-c: Use the built header files in gettext-runtime/intl/.
* gettext-tools/tests/lang-c++: Likewise.
* gettext-tools/tests/lang-objc: Likewise.
