fix failing test on linux

The GNU shell returns a code and no signal if it gets a SIGSEGV
signal, so we have to skip this. Hat tip to @tjfontaine

test/tap/lifecycle-signal.js

@@ -8,10 +8,18 @@ var pkg = path.resolve(__dirname, "lifecycle-signal")
 test("lifecycle signal abort", function (t) {
   // windows does not use lifecycle signals, abort
   if (process.platform === "win32" || process.env.TRAVIS) return t.end()
+
   var child = spawn(node, [npm, "install"], {
     cwd: pkg
   })
   child.on("close", function (code, signal) {
+    // GNU shell returns a code, no signal
+    if (process.platform === "linux") {
+      t.equal(code, 1)
+      t.equal(signal, null)
+      return t.end()
+    }
+
     t.equal(code, null)
     t.equal(signal, "SIGSEGV")
     t.end()