Add quotes around the file name to avoid issues with spaces.

Closes #3719.

Ported to 3.0 from r66145.
diff --git a/Lib/platform.py b/Lib/platform.py
index 27ea1b4..56ab759 100755
--- a/Lib/platform.py
+++ b/Lib/platform.py
@@ -945,7 +945,7 @@
         return default
     target = _follow_symlinks(target)
     try:
-        f = os.popen('file %s 2> /dev/null' % target)
+        f = os.popen('file "%s" 2> /dev/null' % target)
     except (AttributeError,os.error):
         return default
     output = f.read().strip()