Created include/Makefile.in to separate header file installation from
the top-level Makefile.

diff --git a/configure b/configure
index ad343f7..c555732 100755
--- a/configure
+++ b/configure
@@ -4495,6 +4495,7 @@
 graphics/win16drv/Makefile
 graphics/x11drv/Makefile
 if1632/Makefile
+include/Makefile
 ipc/Makefile
 library/Makefile
 libtest/Makefile
@@ -4654,6 +4655,7 @@
 graphics/win16drv/Makefile
 graphics/x11drv/Makefile
 if1632/Makefile
+include/Makefile
 ipc/Makefile
 library/Makefile
 libtest/Makefile