Linking error with qthunspell when building Virtual Keyboard

From the sources of qtvirtualkeyboard, and once added hunspell-distributed (hunspell does not contain dictmgr.cxx so it cannot be used).
When building qtvirtualkeyboard.pro with Qt Creator 4.0.2 in Debug or Release, some linker errors appear :

qthunspell.lib(hashmgr.obj) : error LNK2019: unresolved external symbol "public: __cdecl StrMgr::StrMgr(char const *,char const *)" (??0StrMgr@@QEAA@PEBD0@Z) referenced in function "private: int __cdecl HashMgr::load_config(char const *,char const *,bool)" (?load_config@HashMgr@@AEAAHPEBD0_N@Z)
qthunspell.lib(affixmgr.obj) : error LNK2001: unresolved external symbol "public: __cdecl StrMgr::StrMgr(char const *,char const *)" (??0StrMgr@@QEAA@PEBD0@Z)