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
bazelbuild/bazel#12560

Add --{no,}autodetect_server_javabase
bazelbuild/bazel#12542

This patch also uses the new --noautodetect_server_javabase flag.

Change-Id: I7a397e4a9f17b942d0f81c7affb829d2de385a30

.bazelrc

@@ -96,3 +96,6 @@ build --strategy=TypeScriptCompile=worker --strategy=AngularTemplateCompile=work
 # https://github.com/bazelbuild/bazel/issues/6341 for ongoing discussion with
 # upstream about this.
 build --javabase=@openjdk_linux_archive//:jdk --host_javabase=@openjdk_linux_archive//:jdk
+
+# Prevent falling back to the host JDK.
+startup --noautodetect_server_javabase

doc/make_bazel_package.sh

@@ -9,7 +9,7 @@ set -u
 
 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}"
 
 (

tools/bazel

@@ -24,7 +24,7 @@ if [[ -n "${BAZEL_OVERRIDE+x}" ]]; then
   exec "${BAZEL_OVERRIDE}" "$@"
 fi
 
-readonly VERSION="4.0.0rc2-202012022031+a3c94ec2ed"
+readonly VERSION="4.0.0rc6-202012121845+159e00701d"
 
 readonly DOWNLOAD_DIR="${HOME}/.cache/bazel"
 # Directory to unpack bazel into.  This must change whenever bazel changes.