Fix ContentMain calling in processMain for Windows

ContentMain has a different parameter list for Windows.
Currently no sandbox is in use, just fitting in with the required
parameters. See chromium/content/app/content_main.cc.

Change-Id: I6c3918efaafbf48bd4a07f377be51c22c5355cd0
Reviewed-by: Andras Becsi <andras.becsi@digia.com>
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>
Fix Qt5 libs linking to Qt5WebEngineCore.dll for Windows

MSVC linker needs file extension, otherwise it searches for .obj
files, but Qt has Qt5*.lib files.

Change-Id: I4fd5e1d6001ea309da456c43ffc79cb5944a1ef3
Reviewed-by: Andras Becsi <andras.becsi@digia.com>
Reviewed-by: Pierre Rossi <pierre.rossi@gmail.com>