Pass the linker version to libfuzzer tests on darwin (llvm#87719)

The HOST_LINK_VERSION is a hardcoded string in Darwin clang that detects
the linker version at configure time. The driver uses this information
to build the correct set of arguments for the linker. This patch detects
the linker version again during compiler-rt configuration and passes it
to the libfuzzer tests. This allows a clang built on a machine with a
new linker to run compiler-rt tests on a machine with an old linker.

rdar://125932376

Author: usama54321

compiler-rt/test/fuzzer/lit.cfg.py

@@ -89,6 +89,12 @@ def generate_compiler_cmd(is_cpp=True, fuzzer_enabled=True, msan_enabled=False):
     if fuzzer_enabled:
         sanitizers.append("fuzzer")
     sanitizers_cmd = "-fsanitize=%s" % ",".join(sanitizers)
+
+    if "darwin" in config.available_features and getattr(
+        config, "darwin_linker_version", None
+    ):
+        extra_cmd = extra_cmd + " -mlinker-version=" + config.darwin_linker_version
+
     return " ".join(
         [
             compiler_cmd,