bash-4.3$ norm install mc                                                       
Testing if cc compiles '#define _GNU_SOURCE                                     
#include <stdio.h>                                                              
int main() { printf("Hello, world!\n");; return 0;}' ... no                     
[02/Nov/2021:10:24:36 +0000] [norm] Error: your compiler can't compile!         
[02/Nov/2021:10:24:37 +0000] [norm] Check that your have it installed correctly 

bash-4.3$ # so we copy&paste your test-cc-string in a file ts1.cc
bash-4.3$ cat ts1.cc                                                            
#define _GNU_SOURCE                                                             
#include <stdio.h>                                                              
int main() { printf("Hello, world!\n");; return 0;}                             

bash-4.3$ # and now compile with jor1k-onboard gcc, without errors                                     
bash-4.3$ gcc ts1.cc; a.out                                                     
ts1.cc:1:0: warning: "_GNU_SOURCE" redefined                                    
 #define _GNU_SOURCE                                                            
 ^                                                                              
<command-line>:0:0: note: this is the location of the previous definition  
Hello, world!                                                                   
bash-4.3$