bootstrap: fix bootstrap.py with python2

- import print_function
- wrap buffer, which is required in py3 to read/write bytes (not
  strings) from stdin/stdout, but missing in py2 (gives AttributeError)

bootstrap/bootstrap.py

@@ -1,8 +1,21 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 
+from __future__ import print_function
 import sys
 import struct
 
+def read():
+    try:
+        return sys.stdin.buffer.read()
+    except AttributeError:
+        return sys.stdin.read()
+
+def write(out):
+    try:
+        sys.stdout.buffer.write(out)
+    except AttributeError:
+        sys.stdout.write(out)
+
 def main():
     # read PLAYPAL from stdin, write minimal doom2.wad to stdout
     if sys.stdin.isatty():
@@ -11,7 +24,7 @@ def main():
         sys.exit(1)
 
     # three lumps needed - see bootstrap/README.txt
-    lumps = [(b'PLAYPAL',  sys.stdin.buffer.read()),
+    lumps = [(b'PLAYPAL',  read()),
              (b'TEXTURE1', struct.pack("i", 0)), # empty texture1
              (b'PNAMES',   struct.pack("i8s", 1, b''))] # single pname
 
@@ -23,15 +36,14 @@ def main():
         pos += len(data)
 
     # write wad header
-    wadheader = (b'IWAD', len(waddir), pos)
-    sys.stdout.buffer.write(struct.pack("4sii", *wadheader))
+    write(struct.pack("4sii", b'IWAD', len(waddir), pos))
 
     # write lump contents
     for name, data in lumps:
-        sys.stdout.buffer.write(data)
+        write(data)
 
     # write wad directory
     for i in waddir:
-        sys.stdout.buffer.write(struct.pack("ii8s", *i))
+        write(struct.pack("ii8s", *i))
 
 if __name__ == "__main__": main()