* Restore the patch for D148945, searching /usr/lib/llvm-18/lib by default.

Addresses: #1056580.

debian/changelog

@@ -16,6 +16,8 @@ llvm-toolchain-snapshot (1:18~++20230921012857+4cf8da94198d-1~exp1) UNRELEASED;
   * Also install liborc_rt*.a on ppc64 and ppc64el.
   * Fix stripping build flags on Ubuntu/ppc64el.
   * libclang1-18: Only encode the major version in the soname. See #1056126.
+  * Restore the patch for D148945, searching /usr/lib/llvm-18/lib by default.
+    Addresses: #1056580.
 
   [ John Paul Adrian Glaubitz ]
   * Don't install *clang_rt* on sparc and sparc64

debian/patches/D148945-revert.diff

@@ -0,0 +1,21 @@
+Restore that for now, we're not GenToo ...
+
+https://reviews.llvm.org/D148945
+https://reviews.llvm.org/D122444
+
+--- a/clang/lib/Driver/ToolChains/Linux.cpp
++++ b/clang/lib/Driver/ToolChains/Linux.cpp
+@@ -333,6 +333,13 @@ Linux::Linux(const Driver &D, const llvm
+ 
+   Generic_GCC::AddMultiarchPaths(D, SysRoot, OSLibDir, Paths);
+ 
++  // The deprecated -DLLVM_ENABLE_PROJECTS=libcxx configuration installs
++  // libc++.so in D.Dir+"/../lib/". Detect this path.
++  // TODO Remove once LLVM_ENABLE_PROJECTS=libcxx is unsupported.
++  if (StringRef(D.Dir).startswith(SysRoot) &&
++      D.getVFS().exists(D.Dir + "/../lib/libc++.so"))
++    addPathIfExists(D, D.Dir + "/../lib", Paths);
++
+   addPathIfExists(D, concat(SysRoot, "/lib"), Paths);
+   addPathIfExists(D, concat(SysRoot, "/usr/lib"), Paths);
+ }

debian/patches/series

@@ -146,3 +146,4 @@ force-sse2-compiler-rt.diff
 bolt-disable-emit-relocs.patch
 link-grpc.diff
 libclang-major-version-only.diff
+D148945-revert.diff