Disable the CONFIG_VAR_TX_NO_TX_MODE flag in cmake.

This sets the cmake build config to match default paramters in the
 normal make build system.

Change-Id: I66c6dca1ad7433d90d6f92ab1bc0e568f38c1f23

build/cmake/aom_config_defaults.cmake

diff --git a/build/cmake/aom_config_defaults.cmake b/build/cmake/aom_config_defaults.cmake
index bb0be5c..941ef8b 100644
--- a/build/cmake/aom_config_defaults.cmake
+++ b/build/cmake/aom_config_defaults.cmake
@@ -169,5 +169,5 @@
 set(CONFIG_SBL_SYMBOL 0 CACHE NUMBER "Internal flag.")
 set(CONFIG_NCOBMC_ADAPT_WEIGHT 0 CACHE NUMBER "Internal flag.")
 set(CONFIG_BGSPRITE 0 CACHE NUMBER "Internal flag.")
-set(CONFIG_VAR_TX_NO_TX_MODE 1 CACHE NUMBER "Internal flag.")
+set(CONFIG_VAR_TX_NO_TX_MODE 0 CACHE NUMBER "Internal flag.")
 set(CONFIG_ANALYZER 0 CACHE NUMBER "Internal flag.")