fix: Make local runtime repo work for windows

In particular, this fixes two problems:

First, windows requires interface libraries to be linked in.
Second, windows requires an alternative search path since LIBDIR is not filled in.

Author: EthanSteinberg

python/private/get_local_runtime_info.py

@@ -36,6 +36,8 @@
     # https://stackoverflow.com/questions/47423246/get-pythons-lib-path
     # For now, it seems LIBDIR has what is needed, so just use that.
     "LIBDIR",
+    # A backup alternative for deriving LIBDIR in cases that LIBDIR is not available
+    "LIBDEST",
     # The versioned libpythonX.Y.so.N file. Usually?
     # It might be a static archive (.a) file instead.
     "INSTSONAME",

python/private/local_runtime_repo.bzl

@@ -112,13 +112,22 @@ def _local_runtime_repo_impl(rctx):
         info["INSTSONAME"],
     ]
 
+    if repo_utils.get_platforms_os_name(rctx) == 'windows':
+        shared_lib_names.append("python{major}{minor}.lib".format(**info))
+        shared_lib_names.append("python3.lib")
+
+        interpreter_path = interpreter_path.replace('\\', '/')
+
     # In some cases, the value may be empty. Not clear why.
     shared_lib_names = [v for v in shared_lib_names if v]
 
     # In some cases, the same value is returned for multiple keys. Not clear why.
     shared_lib_names = {v: None for v in shared_lib_names}.keys()
     shared_lib_dir = info["LIBDIR"]
 
+    if shared_lib_dir == None:
+        shared_lib_dir = info["LIBDEST"] + "/../libs"
+
     # The specific files are symlinked instead of the whole directory
     # because it can point to a directory that has more than just
     # the Python runtime shared libraries, e.g. /usr/lib, or a Python

python/private/local_runtime_repo_setup.bzl

@@ -16,6 +16,7 @@
 
 load("@bazel_skylib//lib:selects.bzl", "selects")
 load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("@rules_cc//cc:cc_import.bzl", "cc_import")
 load("@rules_python//python:py_runtime.bzl", "py_runtime")
 load("@rules_python//python:py_runtime_pair.bzl", "py_runtime_pair")
 load("@rules_python//python/cc:py_cc_toolchain.bzl", "py_cc_toolchain")
@@ -58,6 +59,20 @@ def define_local_runtime_toolchain_impl(
     major_minor = "{}.{}".format(major, minor)
     major_minor_micro = "{}.{}".format(major_minor, micro)
 
+    version_dict = {'major': major, 'minor': minor}
+
+    cc_import(
+        name = "interface",
+        interface_library = "lib/python{major}{minor}.lib".format(**version_dict),
+        system_provided = True,
+    )
+
+    cc_import(
+        name = "abi3_interface",
+        interface_library = "lib/python3.lib",
+        system_provided = True,
+    )
+
     cc_library(
         name = "_python_headers",
         # NOTE: Keep in sync with watch_tree() called in local_runtime_repo
@@ -67,6 +82,10 @@ def define_local_runtime_toolchain_impl(
             allow_empty = True,
         ),
         includes = ["include"],
+        deps = select({
+            "@bazel_tools//src/conditions:windows": [":interface", ":abi3_interface"],
+            "//conditions:default": None,
+        }),
     )
 
     cc_library(