Preserve process.execArgv

This ensures flags like `--prof` are passed down to the code-server process so
we can profile everything.

To test this:
1. run `./lib/node --prof .` 
2. in another terminal, run `ps -ejww`

You should see `--prof` next to every code-server process. 

Index: code-server/lib/vscode/src/vs/server/node/extensionHostConnection.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/extensionHostConnection.ts
+++ code-server/lib/vscode/src/vs/server/node/extensionHostConnection.ts
@@ -228,7 +228,7 @@ export class ExtensionHostConnection {
 
 	public async start(startParams: IRemoteExtensionHostStartParams): Promise<void> {
 		try {
-			let execArgv: string[] = [];
+			let execArgv: string[] = process.execArgv ? process.execArgv.filter(a => !/^--inspect(-brk)?=/.test(a)) : [];
 			if (startParams.port && !(<any>process).pkg) {
 				execArgv = [`--inspect${startParams.break ? '-brk' : ''}=${startParams.port}`];
 			}