[misc] Create a gitignore to ignore files

Make git status more useful. Ignore autoconf files, compiled
artefacts, executables and test programs.

openbsc/.gitignore

@@ -0,0 +1,39 @@
+*.o
+*.a
+.deps
+Makefile
+Makefile.in
+bsc_hack
+bsc_msc_ip
+*.*~
+*.sw?
+
+#configure
+aclocal.m4
+autom4te.cache/
+config.log
+config.status
+configure
+depcomp
+install-sh
+missing
+stamp-h1
+
+
+
+# apps and app data
+hlr.sqlite3
+bs11_config
+ipaccess-config
+ipaccess-find
+isdnsync
+
+#tests
+tests/channel/channel_test
+tests/db/db_test
+tests/debug/debug_test
+tests/gsm0408/gsm0408_test
+tests/sccp/sccp_test
+tests/sms/sms_test
+tests/timer/timer_test
+