gcc: arc: add patch to fix tst_movb pattern

Fixes building of quagga [1]:

------------------------------>8---------------------------
839:1: error: unrecognizable insn:
 }
 ^
(insn 183 24 26 4 (set (reg:CC_ZN 61 cc)
        (and:SI (reg:SI 0 r0 [orig:192 _12->id.s_addr ] [192])
            (const_int -256 [0xffffffffffffff00]))) ospf_ri.c:790 -1
     (nil))
ospf_ri.c:839:1: internal compiler error: in extract_insn, at recog.c:2287
------------------------------>8---------------------------

[1] http://autobuild.buildroot.net/results/3c1/3c12c4609d4a77ab8ccd3ea94840884d70520efai



Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>