Change mixed soong/bazel builds to use USE_BAZEL_ANALYSIS

As a result, one can enable bazel-as-ninja-executor separately from
mixed builds.

Test: Manually verified building image with and without bazelenv.sh.
Change-Id: Ia97806fb41e1de850a80b9483ed8a5ff50d9dab2
diff --git a/android/bazel_handler.go b/android/bazel_handler.go
index 210d67a8..221aabc 100644
--- a/android/bazel_handler.go
+++ b/android/bazel_handler.go
@@ -119,7 +119,9 @@
 }
 
 func NewBazelContext(c *config) (BazelContext, error) {
-	if c.Getenv("USE_BAZEL") != "1" {
+	// TODO(cparsons): Assess USE_BAZEL=1 instead once "mixed Soong/Bazel builds"
+	// are production ready.
+	if c.Getenv("USE_BAZEL_ANALYSIS") != "1" {
 		return noopBazelContext{}, nil
 	}
 
diff --git a/bazel/bazelenv.sh b/bazel/bazelenv.sh
index 2ca8baf..fcf71f1 100755
--- a/bazel/bazelenv.sh
+++ b/bazel/bazelenv.sh
@@ -59,12 +59,16 @@
     export BAZEL_PATH="$(which bazel)"
 fi
 
-export USE_BAZEL=1
+# TODO(cparsons): Use USE_BAZEL=1 instead once "mixed Soong/Bazel builds" are
+# production ready.
+export USE_BAZEL_ANALYSIS=1
+# TODO(cparsons): Retrieve this information in either envsetup.sh or 
+# bazel.sh.
 export BAZEL_HOME="$BASE_DIR/bazelhome"
 export BAZEL_OUTPUT_BASE="$BASE_DIR/output"
 export BAZEL_WORKSPACE="$(gettop)"
 
-echo "USE_BAZEL=${USE_BAZEL}"
+echo "USE_BAZEL_ANALYSIS=${USE_BAZEL_ANALYSIS}"
 echo "BAZEL_PATH=${BAZEL_PATH}"
 echo "BAZEL_HOME=${BAZEL_HOME}"
 echo "BAZEL_OUTPUT_BASE=${BAZEL_OUTPUT_BASE}"