image-mklibs: handle position independent binaries

image-mklibs: handle position independent binaries

Executables built with -fpie have the ELF type DYN rather than EXEC
which makes them difficult to distinguish from shared libraries.
Currently when building the list of executables we omit these binaries
so they might fail to run on the resultant rootfs due to missing
symbols. One of these is systemd which builds -fpie unconditionally, so
mklibs breaks images containing systemd.

Modify the search to catch all executable files that are ELF and have an
interpreter set. Omit libc and libpthread as special cases because they
have an interpreter and are directly executable but treating them as
such is antithetical to the pupose of mklibs.

(From OE-Core rev: 30da34ef032d5b4b2f694743715f2c8d64dd9849)

Signed-off-by: Tyler Hall <tylerwhall@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>