ANDROID: Error to use GKI_BUILD_CONFIG_FRAGMENT.

Kleaf has introduced --gki_build_config_fragment for quite a while
to replace GKI_BUILD_CONFIG_FRAGMENT.

Make it an error to use the legacy GKI_BUILD_CONFIG_FRAGMENT.

Bug: 236012223
Change-Id: I27d31c489d0271d7fba922e116cd1f8e6eece801
Signed-off-by: HONG Yifan <elsk@google.com>

build.config.gki.aarch64

@@ -3,5 +3,6 @@
 . ${ROOT_DIR}/${KERNEL_DIR}/build.config.gki
 
 if [ -n "${GKI_BUILD_CONFIG_FRAGMENT}" ]; then
-source ${GKI_BUILD_CONFIG_FRAGMENT}
+    echo "ERROR: GKI_BUILD_CONFIG_FRAGMENT is deprecated; use --gki_build_config_fragment instead.">&2
+    exit 1
 fi

build.config.gki.x86_64

@@ -3,5 +3,6 @@
 . ${ROOT_DIR}/${KERNEL_DIR}/build.config.gki
 
 if [ -n "${GKI_BUILD_CONFIG_FRAGMENT}" ]; then
-source ${GKI_BUILD_CONFIG_FRAGMENT}
+    echo "ERROR: GKI_BUILD_CONFIG_FRAGMENT is deprecated; use --gki_build_config_fragment instead.">&2
+    exit 1
 fi