qemu-error: Avoid build warning.

CC    qemu-error.o
cc1: warnings being treated as errors
/home/edgar/src/c/qemu/git/qemu/qemu-error.c: In function 'error_print_loc':
/home/edgar/src/c/qemu/git/qemu/qemu-error.c:191: error: format not a string literal and no format arguments
make: *** [qemu-error.o] Error 1

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>

qemu-error.c

@@ -188,7 +188,7 @@ void error_print_loc(void)
         error_printf(" ");
         break;
     default:
-        error_printf(sep);
+        error_printf("%s", sep);
     }
 }