Rollup merge of rust-lang#152609 - mati865:gnullvm-llvm-dll, r=bjorn3

Install LLVM DLL in the right place on Windows

Continuation of rust-lang#151795 towards rust-lang#151774.

Unlike other systems, Windows requires runtime libraries to be present in `PATH` or right next to the binary.
So, we copy the library next to the binary as the easier solution.

Tested building `rust-openssl` in debug and release modes, but the difference is within noise margin.

Author: JonathanBrouwer

compiler/rustc_metadata/src/native_libs.rs

@@ -71,6 +71,8 @@ pub fn walk_native_lib_search_dirs<R>(
         || sess.target.os == Os::Fuchsia
         || sess.target.is_like_aix
         || sess.target.is_like_darwin && !sess.sanitizers().is_empty()
+        // FIXME: For the shared LLVM library.
+        || sess.target.os == Os::Windows && sess.target.env == Env::Gnu && sess.target.abi == Abi::Llvm
     {
         f(&sess.target_tlib_path.dir, false)?;
     }

src/bootstrap/src/core/build_steps/dist.rs

@@ -2557,7 +2557,7 @@ pub fn maybe_install_llvm_target(builder: &Builder<'_>, target: TargetSelection,
     ),
 )]
 pub fn maybe_install_llvm_runtime(builder: &Builder<'_>, target: TargetSelection, sysroot: &Path) {
-    let dst_libdir = sysroot.join(builder.sysroot_libdir_relative(Compiler::new(1, target)));
+    let dst_libdir = sysroot.join(builder.libdir_relative(Compiler::new(1, target)));
     // We do not need to copy LLVM files into the sysroot if it is not
     // dynamically linked; it is already included into librustc_llvm
     // statically.

src/ci/github-actions/jobs.yml

@@ -712,6 +712,7 @@ auto:
         --target=aarch64-pc-windows-gnullvm,i686-pc-windows-gnullvm
         --enable-full-tools
         --enable-profiler
+        --enable-llvm-link-shared
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
       CC_i686_pc_windows_gnullvm: i686-w64-mingw32-clang
@@ -724,6 +725,7 @@ auto:
         --build=x86_64-pc-windows-gnullvm
         --enable-full-tools
         --enable-profiler
+        --enable-llvm-link-shared
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
     <<: *job-windows