Add CI.

One of the test suites doesn't seem to work. Have asked on discord, but
I don't think this should block us.

Author: vext01

.buildbot.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+set -e
+
+INST_DIR=`pwd`/inst
+
+mkdir -p build
+cd build
+cmake -DCMAKE_INSTALL_PREFIX=${INST_DIR} \
+    -DLLVM_INSTALL_UTILS=On \
+    -DCMAKE_BUILD_TYPE=release \
+    -DLLVM_ENABLE_ASSERTIONS=On \
+    -DLLVM_ENABLE_PROJECTS="lld;clang" \
+    ../llvm
+make -j `nproc` install
+
+# There are many test suites for LLVM:
+# https://llvm.org/docs/TestingGuide.html
+#
+# This runs unit and integration tests.
+make -j `nproc` check-all
+cd ..
+
+# FIXME The commented code below should run the `test-suite` tests, as
+# described at https://llvm.org/docs/TestSuiteGuide.html.
+#
+# However, the suite fails (even on a stock LLVM) with this error:
+#   retref-bench.cc:17:10: fatal error: 'xray/xray_interface.h' file not found
+#   #include "xray/xray_interface.h"
+#            ^~~~~~~~~~~~~~~~~~~~~~~
+#
+#git clone --depth 1 --branch llvmorg-12.0.0 https://github.com/llvm/llvm-test-suite.git test-suite
+#mkdir -p test-suite-build
+#cd test-suite-build
+#cmake -DCMAKE_C_COMPILER=${INST_DIR}/bin/clang \
+#	-C../test-suite/cmake/caches/O3.cmake \
+#	../test-suite
+#make -j `nproc`
+#llvm-lit -v -j 1 -o results.json .

bors.toml

@@ -0,0 +1,10 @@
+# The service providing the commit statuses to GitHub.
+status = ["buildbot/yk-buildbot-build-script-hw"]
+
+# Allow four hours for builds + tests.
+timeout_sec = 14400
+
+# Have bors delete auto-merged branches
+delete_merged_branches = true
+
+cut_body_after = ""