Add workarounds for loading mke2fs.conf with bazel-built apexer

There are a couple issues when running
pkgutil.get_data('apexer', 'mke2fs.conf') from a bazel-built
apexer binary:

- Soong will take the path to mke2fs.conf as being relative
  to the filegroup that included it, so mke2fs.conf ends up at
  the root of the python zip file, and next to apexer.py.
  Bazel doesn't do this, and instead keeps the mke2fs.conf file
  under a system/extras/ext4_utils folder. Use a genrule to
  explicitly copy mke2fs.conf to the current directory to work
  around this issue.

- pkgutil.get_data() uses python's normal rules for locating
  modules in order to find where the file is. This means it will
  look through sys.path again to find the apexer module. Bazel
  currently has a bug where the first entry in sys.path is the
  location of apexer.py in the source tree, not in the runfiles
  directory. So pkgutil will find apexer.py there, and then
  start looking for mke2fs.conf next to it, and not find it.
  Work around this by deleting sys.path[0].
  bazelbuild/rules_python#382

Bug: 204244290
Test: Presubmits
Change-Id: I9fb9502bff2590abfde95f7f7cc9ebf31157836d

apexer/Android.bp

@@ -49,14 +49,23 @@ python_library_host {
     ],
 }
 
+// This is a hack to move mke2fs_conf into the current folder for bazel builds.
+// Normally bazel would keep it under a system/extras/ext4_utils/ folder.
+genrule {
+    name: "mke2fs_conf_for_apexer",
+    srcs: [":mke2fs_conf"],
+    out: ["mke2fs.conf"],
+    cmd: "cp $(in) $(out)"
+}
+
 python_binary_host {
     name: "apexer",
     srcs: [
         "apexer.py",
     ],
     // TODO(b/157625953) mke2fs.conf can't embedded directly.
     data: [
-        ":mke2fs_conf",
+        ":mke2fs_conf_for_apexer",
     ],
     version: {
         py3: {

apexer/apexer.py

@@ -19,6 +19,16 @@
 
 """
 
+import sys
+
+if len(sys.path) >= 2 and "/execroot/__main__/" in sys.path[1] and "/execroot/__main__/" not in sys.path[0]:
+  # TODO(b/235287972): Remove this hack. Bazel currently has a bug where a path outside
+  # of the execroot is added to the beginning of sys.path, because the python interpreter
+  # will add the directory of the main file to the path, following symlinks as it does.
+  # This can be fixed with the -P option or the PYTHONSAFEPATH environment variable in
+  # python 3.11.0, which is not yet released.
+  del sys.path[0]
+
 import apex_build_info_pb2
 import argparse
 import hashlib
@@ -28,7 +38,6 @@
 import shlex
 import shutil
 import subprocess
-import sys
 import tempfile
 import uuid
 import xml.etree.ElementTree as ET