Don't call abort() directly, always use osmo_panic()

A loooong time ago, we introduced osmo_panic() as a wrapper around
abort().  The advantage is, that this wrapper can be overridden, and
that it will also work in embedded (bare iron) targets, where the
abort simply translates to an infinite loop.

Change-Id: I5a70eb65952cbc329bf96eacb428b07a9da32433
diff --git a/src/bitvec.c b/src/bitvec.c
index 884eb02..0f56e3e 100644
--- a/src/bitvec.c
+++ b/src/bitvec.c
@@ -44,6 +44,7 @@
 
 #include <osmocom/core/bits.h>
 #include <osmocom/core/bitvec.h>
+#include <osmocom/core/panic.h>
 
 #define BITNUM_FROM_COMP(byte, bit)	((byte*8)+bit)
 
@@ -530,7 +531,7 @@
 	case ONE: return '1';
 	case L: return 'L';
 	case H: return 'H';
-	default: abort();
+	default: osmo_panic("unexpected input in bit_value_to_char"); return 'X';
 	}
 }