Build thrift open source build on mac

Summary: `openssl@1.1` is no longer included in Homebrew, in favor of `opennssl@3`.

Reviewed By: iahs

Differential Revision: D100210666

fbshipit-source-id: eb871b11b4f7a5e85eb6ae7cce57f9627ac115e3

Author: sazonovkirill

build/fbcode_builder/getdeps/buildopts.py

@@ -312,7 +312,7 @@ def compute_env_for_install_dirs(
                     # pyre-fixme[6]: For 1st argument expected
                     #  `Union[PathLike[bytes], PathLike[str], bytes, int, str]` but got
                     #  `Optional[str]`.
-                    if os.path.exists(candidate):
+                    if candidate and os.path.exists(candidate):
                         # pyre-fixme[6]: For 2nd argument expected `str` but got
                         #  `Optional[str]`.
                         os.environ["OPENSSL_ROOT_DIR"] = candidate