Pcre2 buck target in third-party (#55)

Summary: Pull Request resolved: meta-pytorch/tokenizers#55

Reviewed By: larryliu0820

Differential Revision: D73412412

Pulled By: jackzhxng

Author: jackzhxng

shim_et/xplat/executorch/build/env_interface.bzl

@@ -47,6 +47,7 @@ _EXTERNAL_DEPS = {
     "nlohmann_json": [], # Intentionally not supporting OSS buck build HF tokenizer.
     "prettytable": "//third-party:prettytable",
     "pybind11": "//third-party:pybind11",
+    "pcre2": "//extension/llm/tokenizers/third-party:pcre2",
     "re2": "//extension/llm/tokenizers/third-party:re2",
     "sentencepiece": [], # Intentionally not supporting OSS buck build of sentencepiece.
     "sentencepiece-py": [],