unix-ffi: Move more unix-only packages to unix-ffi.

With the dependencies captured in manifest.py, several packages in
python-stdlib were still unix-only due to direct or transitive dependencies
on unix-only or ffi modules.  Or they just make no sense to run on
microcontroller targets.

In a few cases (e.g. base64) where possible, the unix dependency could be
removed.

Updates manifest.py to use the `unix_ffi=True` arg to `require()` for these
libraries.

Rename re-pcre to re now that unix-ffi is effectively its own namespace.

Update unix-ffi/README.md, and strengthen the wording that the unix
libraries are unmaintained.

Signed-off-by: Jim Mussared <[email protected]>

Author: jimmo

python-stdlib/base64/base64.py

@@ -96,7 +96,7 @@ def b64decode(s, altchars=None, validate=False):
         altchars = _bytes_from_decode_data(altchars)
         assert len(altchars) == 2, repr(altchars)
         s = s.translate(bytes.maketrans(altchars, b"+/"))
-    if validate and not re.match(b"^[A-Za-z0-9+/]*={0,2}$", s):
+    if validate and not re.match(b"^[A-Za-z0-9+/]*=*$", s):
         raise binascii.Error("Non-base64 digit found")
     return binascii.a2b_base64(s)
 

python-stdlib/base64/manifest.py

@@ -1,7 +1,6 @@
 metadata(version="3.3.3-4")
 
 require("binascii")
-require("re-pcre")
 require("struct")
 
 module("base64.py")