Add hacks to allow tests to run with coverage enabled

When run through `tap` with coverage enabled (`--coverage`) child
processes are wrapped and signal handlers installed which prevent
some of the tests from exiting.

Add workarounds to the affected tests so that the tests can be run
with coverage enabled.

test/test-api-getreport.js

@@ -17,6 +17,12 @@ if (process.argv[2] === 'child') {
                  'Checking no messages on stderr');
   const reportFiles = common.findReports(child.pid);
   tap.same(reportFiles, [], 'Checking no report files were written');
+
+  // tap with coverage enabled wraps the child so adjust expected command line
+  if (process.env['SPAWN_WRAP_SHIM_ROOT']) {
+    args.unshift('.*node');
+  }
+
   tap.test('Validating report content', (t) => {
     common.validateContent(child.stdout, t, { pid: child.pid,
       commandline: process.execPath + ' ' + args.join(' ')

test/test-fatal-error.js

@@ -5,6 +5,10 @@ if (process.argv[2] === 'child') {
   require('../');
 
   const list = [];
+  // tap with coverage enabled installs signal handlers that prevents the
+  // fatal error causing the process to exit. Remove them.
+  process.removeAllListeners('SIGABRT');
+  process.removeAllListeners('SIGTRAP');
   while (true) {
     const record = new MyRecord();
     list.push(record);

test/test-signal.js

@@ -8,6 +8,10 @@ if (process.argv[2] === 'child') {
   // Exit on loss of parent process
   process.on('disconnect', () => process.exit(2));
 
+  // tap with coverage enabled installs signal handlers that prevents the
+  // signal from causing the process to exit. Remove them.
+  process.removeAllListeners('SIGTERM');
+
   function busyLoop() {
     var list = [];
     for (var i = 0; i < 1e10; i++) {