hghave: make different has_pyoxidizer functions have different names

There are 3 of them, and them all having the same name triggered code checkers.

tests/hghave.py

@@ -206,7 +206,7 b' def has_pyoxidizer():'
     "pyoxidizer-in-memory",
     "running with pyoxidizer build as 'hg' with embedded resources",
 )
-def has_pyoxidizer():
+def has_pyoxidizer_mem():
     return 'PYOXIDIZED_IN_MEMORY_RSRC' in os.environ
 
 
@@ -214,7 +214,7 b' def has_pyoxidizer():'
     "pyoxidizer-in-filesystem",
     "running with pyoxidizer build as 'hg' with external resources",
 )
-def has_pyoxidizer():
+def has_pyoxidizer_fs():
     return 'PYOXIDIZED_FILESYSTEM_RSRC' in os.environ