Build fixes to merge vp9-preview into master

Various fixups to resolve issues when building vp9-preview under the more stringent
checks placed on the experimental branch.

Change-Id: I21749de83552e1e75c799003f849e6a0f1a35b07
diff --git a/vpx_scale/vpx_scale.mk b/vpx_scale/vpx_scale.mk
index 3d75932..864af55 100644
--- a/vpx_scale/vpx_scale.mk
+++ b/vpx_scale/vpx_scale.mk
@@ -5,7 +5,9 @@
 SCALE_SRCS-yes += generic/yv12config.c
 SCALE_SRCS-yes += generic/yv12extend.c
 SCALE_SRCS-$(CONFIG_SPATIAL_RESAMPLING) += generic/gen_scalers.c
+SCALE_SRCS-yes += vpx_scale_asm_offsets.c
 SCALE_SRCS-yes += vpx_scale_rtcd.c
+SCALE_SRCS-yes += vpx_scale_rtcd.sh
 
 #neon
 SCALE_SRCS-$(HAVE_NEON)  += arm/neon/vp8_vpxyv12_copyframe_func_neon$(ASM)