asn1_k_decode.c (asn1_decode_krb5_flags): Make the function

asn1_k_decode.c (asn1_decode_krb5_flags): Make the function
	accept bit strings which are less 32 bits long.
	(RFC-1510 makes no guarantee that the length of the bit
	string must be 32 bits long; the old code required that
	the length of the bit string must be exactly 32 bits.)

	Flip the bits with respect to a 32-bit boundary, since
	that's what the old ASN.1 glue code did.  (The values in
	fieldbits.h are encoded backwards, for no good reason.)
	If BACKWARDS_BITMASK_COMPAT is defined, then only flip the
	bits if the high 16 bits are clear and there are some bits set
	in the low 16 bits.  This preserves interoperabilty with
	the old beta 4 distribution, which sent the bit string
	without flipping them around.

asn1_k_encode.c (asn1_encode_krb5_flags): Flip the bits with
	respect to a 32-bit boundary, since that's what the
	old ASN.1 glue code did.  (The values in fieldbits.h
	are encoded backwards, for no good reason.)

krb_asn1.h: #define BACKWARDS_BITMASK_COMPAT.  Add extern
	declaration for asn1_swbits, which is needed for the
	bit reversing code.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@5380 dc483132-0cff-0310-8789-dd5450dbe970