target/generic: add bc to minimal choice as it is required during the kernel build now

target/generic/pkgsel/00-minimal.choice

@@ -2,7 +2,7 @@
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
 # Filename: target/generic/pkgsel/00-minimal.choice
-# Copyright (C) 2006 - 2012 The OpenSDE Project
+# Copyright (C) 2006 - 2014 The OpenSDE Project
 # Copyright (C) 2004 - 2006 The T2 SDE Project
 #
 # More information can be found in the files COPYING and README.
@@ -32,6 +32,7 @@ X dialog
 X autoconf
 X automake
 X bash
+X bc
 X binutils
 X bison
 X bdb