sparc: Set object file format when initializing backend.

Old version breaks for files which do not contain any functions because
in this case, emit_routine never gets called.

ir/be/sparc/bearch_sparc.c

@@ -355,6 +355,9 @@ static arch_env_t *sparc_init(FILE *outfile)
 	*isa = sparc_isa_template;
 	isa->constants = pmap_create();
 
+	be_gas_elf_type_char      = '#';
+	be_gas_object_file_format = OBJECT_FILE_FORMAT_ELF_SPARC;
+
 	be_emit_init(outfile);
 
 	sparc_register_init();

ir/be/sparc/sparc_emitter.c

@@ -1036,9 +1036,6 @@ void sparc_emit_routine(ir_graph *irg)
 	size_t      i;
 	size_t      n;
 
-	be_gas_elf_type_char      = '#';
-	be_gas_object_file_format = OBJECT_FILE_FORMAT_ELF_SPARC;
-
 	heights = heights_new(irg);
 
 	/* register all emitter functions */