tests,misc: Created presubmit.yaml Google Cloud Build files

This will replicate kokoro on Google Cloud services. At present, this
can be run via execution of `gcloud builds submit--config
cloudbuild_presubmit.yaml`.

Jira: https://gem5.atlassian.net/browse/GEM5-271
Change-Id: I5a71ef7fdbe5546b4e6970e4f4641f9e14cc640b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24543
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

cloudbuild_presubmit.yaml

@@ -0,0 +1,31 @@
+steps:
+
+    - name: 'gcr.io/cloud-builders/docker'
+      entrypoint: 'bash'
+      args:
+      - '-c'
+      - |
+        docker pull gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest \
+        || exit 0
+
+    - name: 'gcr.io/cloud-builders/docker'
+      args: ['build',
+             '-t',
+             'gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest',
+             '--cache-from',
+             'gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest',
+             'util/dockerfiles/ubuntu-18.04_all-dependencies']
+
+    - name: 'gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest'
+      entrypoint: 'scons'
+      args: ['build/NULL/unittests.opt', '-j', '4']
+
+    - name: 'gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest'
+      dir: 'tests'
+      entrypoint: 'python'
+      args: ['main.py', 'run', '-j', '4', '--length', 'quick']
+
+images: ['gcr.io/$PROJECT_ID/ubuntu-18.04_all-dependencies:latest']
+options:
+      machineType: 'N1_HIGHCPU_8'
+timeout: 18000s # 5 Hours

util/dockerfiles/ubuntu-18.04_all-dependencies/Dockerfile

@@ -0,0 +1,34 @@
+# Copyright (c) 2020 The Regents of the University of California
+# All Rights Reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met: redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer;
+# redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+FROM ubuntu:18.04
+
+RUN apt -y update
+RUN apt -y upgrade
+RUN apt -y install build-essential git m4 scons zlib1g zlib1g-dev \
+    libprotobuf-dev protobuf-compiler libprotoc-dev libgoogle-perftools-dev \
+    python-dev python python-pip doxygen
+RUN pip install six