Reduce 1 char from progress output for Windows

Windows command prompt force wraps at the maximum number of chars of the
last line so this commit reduces 1 char of it.

Author: aycabta

lib/rdoc/stats/normal.rb

@@ -30,7 +30,7 @@ def print_file files_so_far, filename
     # will be truncated if necessary.
     size = IO.respond_to?(:console_size) ? IO.console_size : IO.console.winsize
     terminal_width = size[1].to_i.nonzero? || 80
-    max_filename_size = terminal_width - progress_bar.size
+    max_filename_size = (terminal_width - progress_bar.size) - 1
 
     if filename.size > max_filename_size then
       # Turn "some_long_filename.rb" to "...ong_filename.rb"