imx-gpu-viv: add apitrace dependency on libpng

This patch is based on the Yocto equivalent:
https://github.com/Freescale/meta-fsl-arm/commit/ce73c200

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/freescale-imx/imx-gpu-viv/Config.in

@@ -62,6 +62,7 @@ config BR2_PACKAGE_PROVIDES_LIBOPENVG
 config BR2_PACKAGE_IMX_GPU_VIV_APITRACE
 	bool "install apitrace tools"
 	select BR2_PACKAGE_IMX_GPU_VIV_G2D
+	select BR2_PACKAGE_LIBPNG
 	help
 	  Copy the apitrace tool to the target. Apitrace consists
 	  of a set of tools to trace, replay and/or inspect OpenGL,

package/freescale-imx/imx-gpu-viv/imx-gpu-viv.mk

@@ -80,6 +80,7 @@ define IMX_GPU_VIV_INSTALL_STAGING_CMDS
 endef
 
 ifeq ($(BR2_PACKAGE_IMX_GPU_VIV_APITRACE),y)
+IMX_GPU_VIV_DEPENDENCIES += libpng
 ifeq ($(IMX_GPU_VIV_LIB_TARGET),x11)
 define IMX_GPU_VIV_INSTALL_APITRACE
 	cp -dpfr $(@D)/apitrace/x11/usr/bin/* $(TARGET_DIR)/usr/bin/