Fallback to 'lib' when 'sys.platlibdir' does not exist.

distutils/command/install.py

@@ -298,7 +298,7 @@ class install(Command):
                             'sys_exec_prefix': exec_prefix,
                             'exec_prefix': exec_prefix,
                             'abiflags': abiflags,
-                            'platlibdir': sys.platlibdir,
+                            'platlibdir': getattr(sys, 'platlibdir', 'lib'),
                            }
 
         if HAS_USER_SITE:

distutils/sysconfig.py

@@ -148,7 +148,7 @@ def get_python_lib(plat_specific=0, standard_lib=0, prefix=None):
         if plat_specific or standard_lib:
             # Platform-specific modules (any module from a non-pure-Python
             # module distribution) or standard Python library modules.
-            libdir = sys.platlibdir
+            libdir = getattr(sys, "platlibdir", "lib")
         else:
             # Pure Python
             libdir = "lib"