libgbm: provide virtual/libgbm for easy switching b/w providers
libgbm: provide virtual/libgbm for easy switching b/w providers

This patch is upstream at meta-ti

commit b2edc511b3c67ea59bb2ae26bc59344406c8c8ae
Follow a similar change in mesa in oe-core:
https://git.openembedded.org/openembedded-core/commit/?id=5f8050722169a931b8e9078b8757216ba7a84506
Signed-off-by: Denys Dmytriyenko <d29de71aea38aad3a87d486929cb0aad173ae612@ti.com>
Signed-off-by: Stefan Müller-Klieser <a3e08e35e4a42be768e7d0e76ae1ba321c2a66dd@phytec.de>

PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec