gh-90473: disable user site packages on WASI/Emscripten (GH-93633)

(cherry picked from commit 5a4af3a)

Co-authored-by: Christian Heimes <christian@python.org>

Author: miss-islington

Lib/site.py

@@ -266,8 +266,8 @@ def _getuserbase():
     if env_base:
         return env_base
 
-    # VxWorks has no home directories
-    if sys.platform == "vxworks":
+    # Emscripten, VxWorks, and WASI have no home directories
+    if sys.platform in {"emscripten", "vxworks", "wasi"}:
         return None
 
     def joinuser(*args):

Lib/sysconfig.py

@@ -111,8 +111,8 @@ def _getuserbase():
     if env_base:
         return env_base
 
-    # VxWorks has no home directories
-    if sys.platform == "vxworks":
+    # Emscripten, VxWorks, and WASI have no home directories
+    if sys.platform in {"emscripten", "vxworks", "wasi"}:
         return None
 
     def joinuser(*args):

Misc/NEWS.d/next/Library/2022-06-09-10-12-55.gh-issue-90473.683m_C.rst

@@ -0,0 +1,2 @@
+Emscripten and WASI have no home directory and cannot provide :pep:`370`
+user site directory.