linux-yocto/4.1: fix gcc7 compilation and v4.1.39

linux-yocto/4.1: fix gcc7 compilation and v4.1.39

Porting the mainline commit, to fix gcc7 builds:

  474c90156c [give up on gcc ilog2() constant optimizations]

We also integrate the 4.1.39 -stable update to pick up additional
fixes.

(From OE-Core rev: 774e0d3f429d383c55e9f54ab095f13694e1d8e6)

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
(cherry picked from commit f0effea8716faae749a7d15003647d68fa0cabf7)
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>