set_flags: remove compression flag

This flag needs to be set BEFORE writing to the file.
But "borg extract" sets the flags last (to support IMMUTABLE),
thus the compression flag would not work as expected.

src/borg/platform/linux.pyx

@@ -126,10 +126,9 @@ BSD_TO_LINUX_FLAGS = {
     stat.UF_NODUMP: FS_NODUMP_FL,
     stat.UF_IMMUTABLE: FS_IMMUTABLE_FL,
     stat.UF_APPEND: FS_APPEND_FL,
-    stat.UF_COMPRESSED: FS_COMPR_FL,
 }
 # must be a bitwise OR of all values in BSD_TO_LINUX_FLAGS.
-LINUX_MASK = FS_NODUMP_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | FS_COMPR_FL
+LINUX_MASK = FS_NODUMP_FL | FS_IMMUTABLE_FL | FS_APPEND_FL
 
 
 def set_flags(path, bsd_flags, fd=None):