While we're at it, let's compile Rcpp with C++11 as well
Resolve ambiguous function call on c++11 (gcc 4.9)

Minimal example to reproduce this error:

    cat <<CPP | gcc -xc++ --std=c++11 -
    #include <cmath>
    #include <iostream>

    using namespace std;

    int main(int argc, char* argv[]) {
        double bla = 2.0;

        if(isnan(bla)) {
            cout<<"Not a number"<<endl;
        }
    }
    CPP

yields:

    <stdin>: In function ‘int main(int, char**)’:
    <stdin>:9:17: error: call of overloaded ‘isnan(double&)’ is ambiguous
    <stdin>:9:17: note: candidates are:
    In file included from /usr/include/features.h:374:0,
                     from /usr/include/x86_64-linux-gnu/c++/4.9/bits/os_defines.h:39,
                     from /usr/include/x86_64-linux-gnu/c++/4.9/bits/c++config.h:430,
                     from /usr/include/c++/4.9/cmath:41,
                     from <stdin>:1:
    /usr/include/x86_64-linux-gnu/bits/mathcalls.h:234:1: note: int isnan(double)
     __MATHDECL_1 (int,isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
     ^
    In file included from <stdin>:1:0:
    /usr/include/c++/4.9/cmath:626:3: note: constexpr bool std::isnan(long double)
       isnan(long double __x)
       ^
    /usr/include/c++/4.9/cmath:622:3: note: constexpr bool std::isnan(double)
       isnan(double __x)
       ^
    /usr/include/c++/4.9/cmath:618:3: note: constexpr bool std::isnan(float)
       isnan(float __x)
       ^
Only need to set a default for JASPS_OWN_R_BINARY_PACKAGE if we build with use_jasps_own_r_binary_package