install asio headers separately to the root include

include/asio/Makefile.am

@@ -0,0 +1,19 @@
+AUTOMAKE_OPTIONS = foreign dist-bzip2 dist-zip
+
+SUBDIRS = include src
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/aclocal.m4 \
+	$(srcdir)/configure \
+	$(srcdir)/config.guess \
+	$(srcdir)/config.sub \
+	$(srcdir)/depcomp \
+	$(srcdir)/install-sh \
+	$(srcdir)/missing \
+	$(srcdir)/mkinstalldirs \
+	$(srcdir)/Makefile.in \
+	asio-*.tar.gz
+
+EXTRA_DIST = \
+	LICENSE_1_0.txt \
+	doc