[LyX/master] CMake: allow compile-time C++ flags to be set

[Kornel Benko]

commit 99c92de8aa77fd9553d72c98013cf89dccd3b468
Author: Kornel Benko <kor...@lyx.org>
Date:   Thu Dec 5 12:00:02 2013 +0100

    CMake: allow compile-time C++ flags to be set
    
    For developper only, therefore the variable is set to advanced.
    
    Ideas from: Scott Kostyshak + Vincent van Ravensteijn

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e72aad5..fa16d10 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -469,8 +469,12 @@ if(NOT MSVC)
        endif()
 endif()
 
+set(LYX_CXX_FLAGS_EXTRA "" CACHE STRING "Desired semicolon separated list of 
extra cxx compile flags, like '-Werror'")
+mark_as_advanced(LYX_CXX_FLAGS_EXTRA)
 if(LYX_CXX_FLAGS_EXTRA)
-       add_definitions(${LYX_CXX_FLAGS_EXTRA})
+       foreach(_flag ${LYX_CXX_FLAGS_EXTRA})
+               add_definitions(${_flag})
+       endforeach()
 endif()
 
 find_package(Qt5Core QUIET)