fix qemu global variable root conflict with function name (#569)

* rename global variable root to binfmt_root

* fix qemu bug

pwndbg/file.py

@@ -33,7 +33,7 @@ def get_file(path, recurse=1):
     local_path = path
 
     if pwndbg.qemu.root() and recurse:
-        return get(os.path.join(pwndbg.qemu.root, path), 0)
+        return get(os.path.join(pwndbg.qemu.binfmt_root, path), 0)
     elif pwndbg.remote.is_remote() and not pwndbg.qemu.is_qemu():
         local_path = tempfile.mktemp()
         error      = None

pwndbg/qemu.py

@@ -61,7 +61,7 @@ def is_qemu_kernel():
 @pwndbg.events.start
 @pwndbg.memoize.reset_on_stop
 def root():
-  global root
+  global binfmt_root
 
   if not is_qemu_usermode():
     return