[LyX/master] Cmake build: Define LYX_USE_CXX11 iff using c++11 extensions after commit 329eae5605d.

[Kornel Benko]

commit a911b1cc658e5e8de90b1fa267f7c7385a95f4c0
Author: Kornel Benko <kor...@lyx.org>
Date:   Wed May 20 12:07:41 2015 +0200

    Cmake build: Define LYX_USE_CXX11 iff using c++11 extensions after commit 
329eae5605d.

diff --git a/development/cmake/config.h.cmake b/development/cmake/config.h.cmake
index 87bf84b..f667d04 100644
--- a/development/cmake/config.h.cmake
+++ b/development/cmake/config.h.cmake
@@ -68,6 +68,9 @@
 // use GNU libstdc++ with C++11 ABI
 #cmakedefine USE_GLIBCXX_CXX11_ABI 1
 
+// use GNU c++11 extensions
+#cmakedefine LYX_USE_CXX11 1
+
 #cmakedefine Z_PREFIX 1
 
 ${Include_used_spellchecker}
diff --git a/development/cmake/modules/FindCXX11Compiler.cmake 
b/development/cmake/modules/FindCXX11Compiler.cmake
index 87a036c..51e236e 100644
--- a/development/cmake/modules/FindCXX11Compiler.cmake
+++ b/development/cmake/modules/FindCXX11Compiler.cmake
@@ -88,6 +88,7 @@ FOREACH(FLAG ${CXX11_FLAG_CANDIDATES})
   IF(CXX11_FLAG_DETECTED)
     SET(CXX11_FLAG "${FLAG}")
     message(STATUS "CXX11_FLAG_DETECTED = \"${FLAG}\"")
+    set(LYX_USE_CXX11 1)
     BREAK()
   ENDIF()
 ENDFOREACH()