Auto-strip option for GNU patch

[Aleksey Midenkov]

That would be a nice feature to auto-detect the value for --strip
option. I never used -p as a feature, rather as an nuisive need to
know the correct -p value. To implement this it is enough to know the
lowest strip level when the directory or patched file exists. There is
no need to do deep search as the simple guess works in 99% of the
cases. In case auto-strip fails patch should fallback to the default
behavior.

-- 
@midenok