Upgrade bazel to 4.0.0rc6

This is the upstream rc6 branch with two cherry-picks:

Fix a couple of bugs with Incompatible Target Skipping
https://github.com/bazelbuild/bazel/pull/12560

Add --{no,}autodetect_server_javabase
https://github.com/bazelbuild/bazel/pull/12542

This patch also uses the new --noautodetect_server_javabase flag.

Change-Id: I7a397e4a9f17b942d0f81c7affb829d2de385a30
diff --git a/doc/make_bazel_package.sh b/doc/make_bazel_package.sh
index 1cd8626..0743bb2 100755
--- a/doc/make_bazel_package.sh
+++ b/doc/make_bazel_package.sh
@@ -9,7 +9,7 @@
 
 BAZEL_SOURCE="$1"
 
-VERSION="4.0.0rc2-$(date +%Y%m%d%H%M)+$(GIT_DIR="${BAZEL_SOURCE}/.git" git rev-parse --short HEAD)"
+VERSION="4.0.0rc6-$(date +%Y%m%d%H%M)+$(GIT_DIR="${BAZEL_SOURCE}/.git" git rev-parse --short HEAD)"
 OUTPUT="bazel_${VERSION}"
 
 (