[lit] Avoid global imports in module declaration

A previous attempt to cleanup module imports broke installing via
pip/setup.py [1].  This should be fixed now.

[1] cf252240e8819d0c90a5e10f773078bdeba33e44

Reviewed By: paquette

Differential Revision: https://reviews.llvm.org/D76940

utils/lit/lit/__init__.py

@@ -6,4 +6,3 @@ __versioninfo__ = (0, 11, 0)
 __version__ = '.'.join(str(v) for v in __versioninfo__) + 'dev'
 
 __all__ = []
-from .main import main

utils/lit/setup.py

@@ -71,7 +71,7 @@ https://github.com/llvm/llvm-project/tree/master/llvm/utils/lit
     packages = find_packages(),
     entry_points = {
         'console_scripts': [
-            'lit = lit:main',
+            'lit = lit.main:main',
             ],
         }
 )