pythongh-67224: Make linecache imports relative to improve startup speed

Lib/linecache.py

@@ -5,9 +5,6 @@
 that name.
 """
 
-import sys
-import os
-
 __all__ = ["getline", "clearcache", "checkcache", "lazycache"]
 
 
@@ -48,6 +45,7 @@ def getlines(filename, module_globals=None):
 
 
 def checkcache(filename=None):
+    import os
     """Discard cache entries that are out of date.
     (This is not checked upon each call!)"""
 
@@ -76,6 +74,9 @@ def checkcache(filename=None):
 
 
 def updatecache(filename, module_globals=None):
+    import os
+    import sys
+
     """Update a cache entry and return its list of lines.
     If something's wrong, print a message, discard the cache entry,
     and return an empty list."""