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/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index dc450cc..1640adc 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -18,9 +18,9 @@
  *
  */
 
-#include <osmocore/gsm0808.h>
-#include <osmocore/protocol/gsm_08_08.h>
-#include <osmocore/gsm48.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/gsm48.h>
 
 #include <arpa/inet.h>