[LyX/master] Assure we use docstring.

[Juergen Spitzmueller]

commit 78c706e02d065301d895af5551937638921a0f97
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Mon Nov 16 08:21:53 2015 +0100

    Assure we use docstring.
    
    Cures another monolithic build error with CMake.

diff --git a/src/frontends/qt4/GuiBibtex.cpp b/src/frontends/qt4/GuiBibtex.cpp
index 556b79c..8c35ced 100644
--- a/src/frontends/qt4/GuiBibtex.cpp
+++ b/src/frontends/qt4/GuiBibtex.cpp
@@ -329,10 +329,10 @@ void GuiBibtex::updateContents()
 
        docstring const & btprint = params_["btprint"];
        int btp = 0;
-       if ((bibtopic && btprint == "btPrintNotCited") ||
-          (!bibtopic && btprint == "btPrintAll"))
+       if ((bibtopic && btprint == from_ascii("btPrintNotCited")) ||
+          (!bibtopic && btprint == from_ascii("btPrintAll")))
                btp = 1;
-       else if (bibtopic && btprint == "btPrintAll")
+       else if (bibtopic && btprint == from_ascii("btPrintAll"))
                btp = 2;
 
        btPrintCO->setCurrentIndex(btp);