__global became a new keyword.
Legacy code can use __global and compiler produce error messages if the keyword __global is used as an identifier.
To workaround the problem, add 
#pragma disable_ldscope
to the beginning of acompilation unit and 
#pragma enable_ldscope
to the end
Between pragmas you can use __global as an identifier.
Code examole:

#pragma disable_ldscope
int __global = 8;
#pragma enable_ldscope
int main(int argc, char**argv) {
    return 0;
}