[meta-freescale] jethro/i.MX6 build failure without x11

[Francesco Dolcini]

Hi All,
build is failing if x11 is removed from distro feature (build with FB backend)

Loaded 2382 entries from dependency cache.
NOTE: Resolving any missing task queue dependencies
NOTE: multiple providers are available for jpeg (jpeg, libjpeg-turbo)
NOTE: consider defining a PREFERRED_PROVIDER entry to match jpeg
ERROR: Nothing RPROVIDES 'libgl-mesa-dev' (but .... ../sources/meta-fsl-arm/recipes-graphics/imx-gpu-viv/imx-gpu-viv_5.0.11.p7.4-hfp.bb RDEPENDS on or otherwise requires it)
NOTE: Runtime target 'libgl-mesa-dev' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['libgl-mesa-dev']
NOTE: Runtime target 'fsl-gpu-sdk' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['fsl-gpu-sdk', 'virtual/libgles2', 'libgl-mesa-dev']
NOTE: Runtime target 'packagegroup-fsl-tools-gpu' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['packagegroup-fsl-tools-gpu', 'fsl-gpu-sdk', 'virtual/libgles2', 'libgl-mesa-dev']

The problem seems exactly this one: https://lists.yoctoproject.org/pipermail/yocto/2015-November/027467.html

Removing RDEPENDS_libgl-mx6-dev += "libgl-mesa-dev" solves the problem, but it does not seem the righ solution.
Any suggestion on what is the correct fix?

Thanks,
Francesco