include: reorganize headers file to include/osmocom/[gsm|core]

This patch moves all GSM-specific definitions to include/osmocom/gsm.
Moreover, the headers in include/osmocore/ have been moved to
include/osmocom/core.

This has been proposed by Harald Welte and Sylvain Munaunt.

Tested with `make distcheck'.

Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
diff --git a/include/osmocom/vty/telnet_interface.h b/include/osmocom/vty/telnet_interface.h
index 444e649..0c034e4 100644
--- a/include/osmocom/vty/telnet_interface.h
+++ b/include/osmocom/vty/telnet_interface.h
@@ -21,8 +21,8 @@
 #ifndef TELNET_INTERFACE_H
 #define TELNET_INTERFACE_H
 
-#include <osmocore/logging.h>
-#include <osmocore/select.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/select.h>
 
 #include <osmocom/vty/vty.h>