Consolidate linker argument handling for applications and shared libs.
Consolidate linker argument handling for applications and shared libs.

As a side effect, this fixes a bug where cpp.embedInfoPlist would have
no effect for shared libraries, cpp.entryPoint would have no effect for
applications, and some MinGW options weren't applied for DLLs.

Change-Id: I61f5f0ea4ad882cbd9aa93608837e0951b0dca0d
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@digia.com>

Distrotech/qbs,Distrotech/qbs,qt-labs/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,Distrotech/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,villytiger/qbs,gatzka/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,Distrotech/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,Distrotech/qbs,villytiger/qbs,villytiger/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,Distrotech/qbs,qt-labs/qbs,qt-labs/qbs