mkelfimage: Fix cross build

mkelfimage: Fix cross build

This patch fixes building this tool in cross environment
It uses tools such as CC, HOST_CC, I386_CC etc.
and as long as you are building native it does not
matter since they all are same namely 'gcc' but
in cross compiling that wont work. So we make the
makefiles and configure scripts aware of that fact

Upstream hosts this program in a svn repo. So change
the SRC_URI to official svn repo. With git we were
checking out a lot more that just mkelfimage which
is not required.

There were unpackaged empty directories too so
we make sure they are removed as well.

Fixes Yocto bug# 2765

(From OE-Core rev: 0d828f19f7ef2d852bbe6da4510efea76a39b982)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>