outdated .socopy is causing undefined reference link error

in project with dll + application, the dll .socopy folder gets outdated (not same modification date as the one just built)
This is causing undefined reference when building the exe.

attached patch 0001 describes a minimal qbs project with dll and application
attached patch 0002 adds another symbol to the dll API and triggers the bug

Steps to reproduce:

• git init
• git apply 0001-initial-commit.patch
• build and run
• git apply 0002-add-another-symbol.patch
• build

qbsbug/qbsbug_app/main.cpp:7: undefined reference to `imp__ZN2qb16useAnotherSymbolEv'