bitbake-layers: print the recipe's depends that crosses a layer boundary

Figure out the dependency between recipes that crosses a layer boundary

* Introduction:
  - For the .bb file, we need check the following depends:
    > Check the DEPENDS, RDEPENDS and inherits according to the
      cooker_data.
    > The cooker_data doesn't have the info about "require/include xxx",
      so we need check them manually.

  - For the .bbclass, .inc and .conf file, we can't get their file
    depends from the cooker_data, we need check them manually.

* Usage:
  $ bitbake-layer show-cross-depends

  I don't like the name "show-cross-depends", figure-out-cross-depends
  might be better, but most of the commands are "show-xxx" for bitbake-layers.

* Output: (snipped)
/work/poky/meta/recipes-support/libusb/libusb-compat_0.1.4.bb inherits /work/poky/meta-yocto/classes/poky-sanity.bbclass
/work/poky/meta-intel/meta-cedartrail/recipes-cdv-media/images/core-image-cdv-media.bb requires /work/poky/meta/recipes-sato/images/core-image-sato.bb
/work/poky/meta-yocto/recipes-core/tiny-init/tiny-init.bb RDEPENDS /work/poky/meta/recipes-core/busybox/busybox_1.20.2.bb
/work/poky/meta-intel/common/recipes-bsp/amt/lms_7.1.20.bb DEPENDS /work/poky/meta/recipes-devtools/autoconf/autoconf_2.69.bb
/work/poky/meta/classes/distrodata.bbclass includes /work/poky/meta-yocto/conf/distro/include/package_regex.inc
/work/poky/meta-intel/meta-sys940x/conf/machine/sys940x.conf requires /work/poky/meta/conf/machine/include/tune-atom.inc

[YOCTO #3387]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>