More on C++11 requirements

[Marcus D. Leech]

Playing with a project (gr-radio_astro from WVURAIL: 
https://github.com/WVURAIL/gr-radio_astro), and running into compile 
issues on
   older OS (Fedora 20 in this case).

Now, the interesting thing is that my GCC appears to have support for  
c++11  (since -std=c++11 works as a command arg), and despite the
  fact that the CMakelists.txt file for the project includes:

########################################################################
# Compiler specific setup
########################################################################
if(CMAKE_COMPILER_IS_GNUCXX AND NOT WIN32)
    #http://gcc.gnu.org/wiki/Visibility
    add_definitions(-fvisibility=hidden)
    set(CMAKE_CXX_STANDARD 11)
endif()

There doesn't appear to be any use of -std=c++11   in the Make files 
generated, and one gets compile errors for source that includes
  C++11 features/syntax.

Are there extra "sets" in the CMakeLists.txt that I should be using to 
force it to use the c++11 compiler options?

Cheers