mali-t76x: depends on mesa3d-headers

It selects them, but doesn't depend on them, and since the package only
provides binaries there's a complete lack of headers. When some other
package pulls in the egl/gles provider this doesn't result in headers
being pulled in, hence the API is completely missing. Fixes:
http://autobuild.buildroot.net/results/dab/dab91372b7bfde57796a7e3de7e823dc44adfb76/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/mali-t76x/mali-t76x.mk

@@ -7,7 +7,7 @@
 MALI_T76X_VERSION = r5p0-06rel0
 MALI_T76X_SOURCE = mali-t76x_$(MALI_T76X_VERSION)_linux_1+fbdev.tar.gz
 MALI_T76X_SITE = http://malideveloper.arm.com/downloads/drivers/binary/$(MALI_T76X_VERSION)
-
+MALI_T76X_DEPENDENCIES = mesa3d-headers
 MALI_T76X_INSTALL_STAGING = YES
 MALI_T76X_PROVIDES = libegl libgles