Split include/Makefile.am content into subdirs

When someone is modifying a given library there's no need to be looking
at a common file contains tons of lines from different libraries.
Furthermore, this removes the need of "nobase" autofoo prefix, hence
following the usual directive of having one Makefile per directory.

Change-Id: I785891c2f89114bf8303c799094b637d3d25ac71
diff --git a/configure.ac b/configure.ac
index 5f70fca..9c9681d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -585,6 +585,19 @@
 	libosmosim.pc
 	libosmousb.pc
 	include/Makefile
+	include/osmocom/Makefile
+	include/osmocom/codec/Makefile
+	include/osmocom/coding/Makefile
+	include/osmocom/core/Makefile
+	include/osmocom/crypt/Makefile
+	include/osmocom/ctrl/Makefile
+	include/osmocom/gprs/Makefile
+	include/osmocom/gprs/protocol/Makefile
+	include/osmocom/gsm/Makefile
+	include/osmocom/gsm/protocol/Makefile
+	include/osmocom/sim/Makefile
+	include/osmocom/usb/Makefile
+	include/osmocom/vty/Makefile
 	src/Makefile
 	src/core/Makefile
 	src/vty/Makefile