libcommon-cs: move a_reset.c into libbsc

a_reset.c was originally used by both libmsc and libbsc in the old openbsc.git
repository. Now osmo-msc.git has its own copy, and the idea of sharing
libcommon-cs is no longer applicable. Move it to libbsc where it belongs.

Change-Id: I30e4b5dab9c6d761d20a3a0e5b9ec2d65e64ebc5
diff --git a/src/libbsc/Makefile.am b/src/libbsc/Makefile.am
index f03b498..e68ada8 100644
--- a/src/libbsc/Makefile.am
+++ b/src/libbsc/Makefile.am
@@ -27,6 +27,7 @@
 	abis_om2000.c \
 	abis_om2000_vty.c \
 	abis_rsl.c \
+	a_reset.c \
 	bsc_rll.c \
 	bsc_subscriber.c \
 	paging.c \