Allow blocklisting dependencies.

A few crates have patches that manually remove a dependency that
cargo2android.py adds.  This option can allow us to remove those
patches.

Test: Use when running on a few crates.
Change-Id: Ie8337789ab232fb726ccfe361df489acfdd31b20
diff --git a/scripts/cargo2android.py b/scripts/cargo2android.py
index 2ab58e1..c6a35cd 100755
--- a/scripts/cargo2android.py
+++ b/scripts/cargo2android.py
@@ -822,6 +822,8 @@
         lib_name = groups.group(1)
       else:
         lib_name = re.sub(' .*$', '', lib)
+      if lib_name in self.runner.args.dependency_blocklist:
+        continue
       if lib.endswith('.rlib') or lib.endswith('.rmeta'):
         # On MacOS .rmeta is used when Linux uses .rlib or .rmeta.
         rust_libs += '        "' + altered_name('lib' + lib_name) + '",\n'
@@ -1602,6 +1604,11 @@
       nargs='*',
       help='Mark the main library as apex_available with the given apexes.')
   parser.add_argument(
+      '--dependency-blocklist',
+      nargs='*',
+      default=[],
+      help='Do not emit the given dependencies.')
+  parser.add_argument(
       '--no-test-mapping',
       action='store_true',
       default=False,