Revert "circt: Drop dylib patch, just working around for now."

This reverts commit 9737aba.

circt.nix

@@ -51,6 +51,7 @@ in stdenv.mkDerivation {
  ./patches/circt-mlir-tblgen-path.patch
  ./patches/circt-mlir-cpu-runner-target.patch
  ./patches/circt-install-dir.patch
+ ./patches/circt-lit-dylib-paths.patch
  ];
  postPatch = ''
  substituteInPlace cmake/modules/GenVersionFile.cmake \

patches/circt-lit-dylib-paths.patch

@@ -0,0 +1,49 @@
+From be96ffaae1e9cdbc53151ba1797bf6dc111c5dae Mon Sep 17 00:00:00 2001
+From: Will Dietz <will.dietz@sifive.com>
+Date: Fri, 10 May 2024 12:43:46 -0500
+Subject: [PATCH] dylib-lit-paths
+
+lit.cfg.py only, leave Unit as-is for now.
+---
+ test/lit.cfg.py | 28 ++++++++++++++++++++++++++++
+ 1 file changed, 28 insertions(+)
+
+diff --git a/test/lit.cfg.py b/test/lit.cfg.py
+index 009a561a5..abbf72a60 100644
+--- a/test/lit.cfg.py
++++ b/test/lit.cfg.py
+@@ -90,3 +90,31 @@ if config.slang_frontend_enabled:
+ tools.append('circt-verilog')
+
+ llvm_config.add_tool_substitutions(tools, tool_dirs)
++
++
++def find_shlibpath_var():
++ if platform.system() in ["Linux", "FreeBSD", "NetBSD", "OpenBSD", "SunOS"]:
++ yield "LD_LIBRARY_PATH"
++ elif platform.system() == "Darwin":
++ yield "DYLD_LIBRARY_PATH"
++ elif platform.system() == "Windows":
++ yield "PATH"
++ elif platform.system() == "AIX":
++ yield "LIBPATH"
++
++
++for shlibpath_var in find_shlibpath_var():
++ # in stand-alone builds, shlibdir is clang's build tree
++ # while llvm_libs_dir is installed LLVM (and possibly older clang)
++ shlibpath = os.path.pathsep.join(
++ (
++ config.circt_shlib_dir,
++ config.environment.get(shlibpath_var, ""),
++ )
++ )
++ config.environment[shlibpath_var] = shlibpath
++ break
++else:
++ lit_config.warning(
++ "unable to inject shared library path on '{}'".format(platform.system())
++ )
+-- 
+2.39.3 (Apple Git-146)
+