cmake; fix missing rtcd dep for obudec.c

parallel builds could fail if obudec.c was built before rtcd generation
as it relies on internal headers

Change-Id: I46e2fd9cedfd929591c7b191ebd3f2bf8a566e16

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 60ccfec..a3b2046 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -308,6 +308,10 @@
   add_library(aom_common_app_util OBJECT ${AOM_COMMON_APP_UTIL_SOURCES})
   if (CONFIG_AV1_DECODER)
     add_library(aom_decoder_app_util OBJECT ${AOM_DECODER_APP_UTIL_SOURCES})
+    # obudec depends on internal headers that require *rtcd.h
+    if (CONFIG_OBU_NO_IVF)
+      add_dependencies(aom_decoder_app_util aom_rtcd)
+    endif ()
   endif ()
   if (CONFIG_AV1_ENCODER)
     add_library(aom_encoder_app_util OBJECT ${AOM_ENCODER_APP_UTIL_SOURCES})