[oe] base.bbclass: Enable overwrite flag for unzip command

[Leon Woestenberg]

Hello,

During rebuilds I noticed unpacking a zip a second time fails, whereas tar
silently succeeds, overwriting files.

A manual test confirms this:

leon at witty:/tmp$ unzip -q
/home/leon/sandbox/efika/openembedded/downloads/faad2-2.0.zip
leon at witty:/tmp$ unzip -q
/home/leon/sandbox/efika/openembedded/downloads/faad2-2.0.zip
replace faad2/aacDECdrop/aacDECdrop/aacDECdrop.dsp? [y]es, [n]o, [A]ll,
[N]one, [r]ename: leon at witty:/tmp$

leon at witty:/tmp$ tar xzf ~/sandbox/efika/openembedded/downloads/zeroconf-
0.9.tar.gz
leon at witty:/tmp$ tar xzf ~/sandbox/efika/openembedded/downloads/zeroconf-
0.9.tar.gz

I will shortly commit the following change (after a test), which enables
overwrite behaviour for unzip:

-base.bbclass:574:               cmd = 'unzip -q'
+base.bbclass:574:               cmd = 'unzip -q -o'

Regards,
-- 
Leon