binutils-2.20.1: fix checksums as 2.20.1 is now 2.20.1a

2.20.1 is now 2.20.1a (but when extracting the 2.20.1a sources, the
directory name is still 2.20.1)

$ LANG=C diff -rq binutils-2.20.1 binutils-2.20.1a
Only in binutils-2.20.1a: cgen
Files binutils-2.20.1/md5.sum and binutils-2.20.1a/md5.sum differ
Files binutils-2.20.1/opcodes/m32c-desc.c and binutils-2.20.1a/opcodes/m32c-desc.c differ
Files binutils-2.20.1/opcodes/mep-asm.c and binutils-2.20.1a/opcodes/mep-asm.c differ
Files binutils-2.20.1/opcodes/mep-opc.c and binutils-2.20.1a/opcodes/mep-opc.c differ

Signed-off-by: Eric Bénard <eric@eukrea.com>
Acked-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>