Query terminal width from STDOUT_FILENO

Rather than 0 (stdin). So it will work even if ninja's stdin isn't connected to
the terminal for whatever reason.
diff --git a/src/line_printer.cc b/src/line_printer.cc
index 2cd3e17..6bf9e1b 100644
--- a/src/line_printer.cc
+++ b/src/line_printer.cc
@@ -82,7 +82,7 @@
     // Limit output to width of the terminal if provided so we don't cause
     // line-wrapping.
     winsize size;
-    if ((ioctl(0, TIOCGWINSZ, &size) == 0) && size.ws_col) {
+    if ((ioctl(STDOUT_FILENO, TIOCGWINSZ, &size) == 0) && size.ws_col) {
       to_print = ElideMiddle(to_print, size.ws_col);
     }
     printf("%s", to_print.c_str());