Add generic_analysis example that performs coverage analysis (#1072)

This adds an example script and tool that enables LLVM source-based coverage using the `generic_analysis` task.

This provides:
1. sample python script that launches the template and then the analysis task
1. sample `analysis_exe` wrapper script that launches the LLVM coverage tools
1. sample libfuzzer target for the example
1. walk through submitting the jobs and inspecting the results

src/cli/examples/llvm-source-coverage/tools/source-coverage.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+#
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+set -ex
+
+if [ $# -lt 3 ]; then
+    echo usage: FUZZER RESULT_DIR FILE [... FILE_N]
+    exit 1
+fi
+
+FUZZER=$1; shift
+RESULTS=$1; shift
+
+mkdir -p ${RESULTS}/inputs
+
+MERGED=${RESULTS}/coverage.profdata
+REPORT=${RESULTS}/coverage.report
+LCOV=${RESULTS}/coverage.lcov
+
+COV_TOOL=$(which llvm-cov || which llvm-cov-10)
+PROF_TOOL=$(which llvm-profdata || which llvm-profdata-10)
+
+for file in $@; do
+    SHA=$(sha256sum ${file} | cut -d ' ' -f 1)
+    RAW=${RESULTS}/inputs/${SHA}.profraw
+
+    if [ -f ${RAW} ]; then
+        continue
+    fi
+    
+    LLVM_PROFILE_FILE=${RAW} ${FUZZER} ${file}
+    if [ ! -f ${RAW} ]; then
+        echo "no coverage file generated ${RAW}"
+        exit 1
+    fi
+
+    if [ -f ${MERGED} ]; then
+        ${PROF_TOOL} merge -output ${MERGED}.tmp ${RAW} ${MERGED}
+        mv ${MERGED}.tmp ${MERGED}
+    else 
+        ${PROF_TOOL} merge -output ${MERGED} ${RAW}
+    fi
+
+    ${COV_TOOL} export ${FUZZER} -instr-profile=${MERGED} > ${REPORT}
+    ${COV_TOOL} export ${FUZZER} -instr-profile=${MERGED} --format lcov > ${LCOV}
+done