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/bitvec.c b/src/bitvec.c
index 95d78a5..4984af2 100644
--- a/src/bitvec.c
+++ b/src/bitvec.c
@@ -24,7 +24,7 @@
 #include <errno.h>
 #include <stdint.h>
 
-#include <osmocore/bitvec.h>
+#include <osmocom/core/bitvec.h>
 
 #define BITNUM_FROM_COMP(byte, bit)	((byte*8)+bit)