minigbm: Add AMDGPU minigbm driver

Add a minigbm driver to support the AMDGPU drm.

BUG=chrome-os-partner:56076
TEST=emerge-jadeite minigbm and test UI

Change-Id: I395bba57998d95074bd13a379d62d6bec888154b
Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
Reviewed-on: https://chromium-review.googlesource.com/368101
Tested-by: Dominik Behr <dbehr@chromium.org>
Reviewed-by: Dominik Behr <dbehr@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
diff --git a/Makefile b/Makefile
index ed3956e..ccc26c7 100644
--- a/Makefile
+++ b/Makefile
@@ -11,6 +11,10 @@
 CPPFLAGS += -std=c99 -D_GNU_SOURCE=1
 CFLAGS += -Wall -Wsign-compare -Wpointer-arith -Wcast-qual -Wcast-align
 
+ifdef DRV_AMDGPU
+	CFLAGS += $(shell $(PKG_CONFIG) --cflags libdrm_amdgpu)
+	LDLIBS += -lamdgpuaddr
+endif
 ifdef DRV_EXYNOS
 	CFLAGS += $(shell $(PKG_CONFIG) --cflags libdrm_exynos)
 endif