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/select.c b/src/select.c
index 5aa2beb..adf3619 100644
--- a/src/select.c
+++ b/src/select.c
@@ -22,9 +22,9 @@
 #include <fcntl.h>
 #include <stdio.h>
 
-#include <osmocore/select.h>
-#include <osmocore/linuxlist.h>
-#include <osmocore/timer.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
 
 #include "../config.h"