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/core/Makefile.am b/include/osmocom/core/Makefile.am
new file mode 100644
index 0000000..6109f47
--- /dev/null
+++ b/include/osmocom/core/Makefile.am
@@ -0,0 +1,12 @@
+osmocore_HEADERS = signal.h linuxlist.h timer.h select.h msgb.h bits.h \
+		   bitvec.h statistics.h utils.h \
+		   gsmtap.h write_queue.h \
+		   logging.h rate_ctr.h gsmtap_util.h \
+		   plugin.h crc16.h panic.h process.h msgfile.h \
+		   backtrace.h
+
+if ENABLE_TALLOC
+osmocore_HEADERS += talloc.h
+endif
+
+osmocoredir = $(includedir)/osmocom/core