autotools/windres: use AC_PROG_SED for sed sed is actually surprisingly unportable. on mingw this shouldn't be a problem, but alas, we should use it anyway

lib_LTLIBRARIES = libpugixml.la
libpugixml_la_SOURCES = src/pugixml.cpp
include_HEADERS = src/pugixml.hpp

ACLOCAL_AMFLAGS = -I m4