[bazel] Use in-tree openssl for Rust openssl-sys

Signed-off-by: Yi-Hsuan Deng <yhdeng@google.com>
Change-Id: If6b2be221d2330cbe42062f8cd061da26a6a6964

Author: sasdf

MODULE.bazel

@@ -157,12 +157,18 @@ crate.annotation(
     },
     repositories = ["crate_index"],
 )
+
+inject_repo(
+    crate,
+    ot_openssl = "openssl",
+)
+
 crate.annotation(
+    build_script_data = ["@ot_openssl//:gen_dir"],
     build_script_env = {
-        "PKG_CONFIG_PATH": "$(OPENSSL_PKG_CONFIG_PATH)",
+        "OPENSSL_DIR": "$(execpath @ot_openssl//:gen_dir)",
         "OPENSSL_STATIC": "1",
     },
-    build_script_toolchains = ["@lowrisc_opentitan//third_party/rust:openssl_pkg_config_path"],
     crate = "openssl-sys",
     repositories = ["crate_index"],
 )

MODULE.bazel.lock

@@ -13,12 +13,6 @@ config_setting(
     values = {"define": "SPECIFY_BINDGEN_LIBSTDCXX=true"},
 )
 
-string_flag(
-    name = "openssl_pkg_config_path",
-    build_setting_default = "",
-    make_variable = "OPENSSL_PKG_CONFIG_PATH",
-)
-
 # Since rules_rust 0.23.0, bindgen depends on the llvm project and builds the
 # llvm libaries from source. Building llvm from source has a huge impact on
 # build times. Instead, we depend on a pre-built llvm release and instantiate