fix(fpm_compile_commands): Add thread safety (OpenMP critical) to command registration

Author: zoziha

src/fpm_compile_commands.F90

@@ -287,7 +287,9 @@ subroutine cct_register(self, command, target_os, error)
                                 file = string_t(source_file))
 
         ! Add it to the structure
+        !$omp critical (command_update)
         call cct_register_object(self, cmd, error)
+        !$omp end critical (command_update)
 
     end subroutine cct_register