Makefile exit on error, add QUIET variable.

This will show warnings and errors:
    make QUIET=

Makefile

@@ -1,7 +1,8 @@
 CFLAGS = -O3 -static
+QUIET = 2>/dev/null
 
 h: h.c
-	@a="g++ -fpermissive -includestdlib.h -includestdio.h -O3 -static -Wl,--omagic h.c -oh -DS=M=*d,*d=*c,*c=M -DD=0x0";$$a 2>/dev/null;$$a`nm h|grep qm|sed 's/0 .*$$/1/'` 2>/dev/null; echo "Now run ./h"
+	@a="g++ -fpermissive -includestdlib.h -includestdio.h -O3 -static -Wl,--omagic h.c -oh -DS=M=*d,*d=*c,*c=M -DD=0x0";$$a $(QUIET)&&$$a`nm h|grep qm|sed 's/0 .*$$/1/'` $(QUIET)&&echo "Now run ./h"
 
 clean:
 	rm h