I want to port https://github.com/apple/swift/pull/3923 to swift-corelibs-libdispatch but I can't figure out how to build swift-corelibs-libdispatch on OS X. Running `sh autogen.sh` results in
src/Makefile.am:9: error: Libtool library used but 'LIBTOOL' is undefined
src/Makefile.am:9: The usual way to define 'LIBTOOL' is to add 'LT_INIT'
src/Makefile.am:9: to 'configure.ac' and run 'aclocal' and 'autoconf' again.
src/Makefile.am:9: If 'LT_INIT' is in 'configure.ac', make sure
src/Makefile.am:9: its definition is in aclocal's search path.
configure.ac does include LT_INIT, but I have no idea how to make sure its definition is in aclocal's search path.
I get the same problem with swift/utils/build-script --libdispatch.