Install programs into $(prefix)/bin, not /sbin

At least in many configurations, there is no need to run any
of our programs as root.  Thus, we shouldn't install them in sbin.
diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index 077054c..50c9b1a 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -13,7 +13,7 @@
 SUBDIRS += bsc
 endif
 
-sbin_PROGRAMS = bsc_hack bs11_config isdnsync bsc_mgcp
+bin_PROGRAMS = bsc_hack bs11_config isdnsync bsc_mgcp
 noinst_LIBRARIES = libbsc.a libmsc.a libvty.a libmgcp.a
 
 libbsc_a_SOURCES = abis_rsl.c abis_nm.c abis_om2000.c gsm_data.c gsm_04_08_utils.c \