[Bug 34013] New: Altium Designer 10 installer crashes in InternetQueryOptionW

http://bugs.winehq.org/show_bug.cgi?id=34013

Bug #: 34013
           Summary: Altium Designer 10 installer crashes in
                    InternetQueryOptionW
           Product: Wine
           Version: 1.6-rc4
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: wininet
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]
    Classification: Unclassified

After doing 'winetricks vd=1024x768' to work around bug 34012,
continued with Altium Designer install.  Next problem was
it refused to accept my username and password.

+relay,+seh,+wininet showed that it was crashing in InternetQueryOptionW()
somehow.  The installer caught the crash, so there was no backtrace, but it
did give the address in the gui and said it was a read from NULL.
Passing that address to winedbg's disasm pointed to str_to_buffer().
The option it was retrieving was INTERNET_OPTION_PROXY_USERNAME; 
evidently req->session->appInfo->proxyUsername was null.

This may be a regression introduced by the recent commit
bedf296a27d5689beb693637407829b0bd6d8a1c

The attached patch gets past this problem and on to the next.