[K/N] Use LLD 12.0.1 for MinGW targets

Clang-produced and GCC-produced binaries might be ABI-incompatible on
MinGW. Explanation on GitHub: msys2/MINGW-packages/issues/6855#issuecomment-680859662.
TL;DR: GCC-generated sections are 16-byte-padded, while Clang ones are
not. It causes problems during merge of COMDAT sections.
I observed the problem during compilation of runtime tests, but it is
possible that the problem could affect main compilation pipeline as well.
https://reviews.llvm.org/D86659 (which landed in LLVM 12) fixes
the problem. So we have another motivation for switching to LLD besides
https://youtrack.jetbrains.com/issue/KT-47605.

The only known downside is unsupported defsym which causes slight binary
size increase. I think it is doable.

kotlin-native/shared/src/main/kotlin/org/jetbrains/kotlin/konan/target/Linker.kt

@@ -441,11 +441,6 @@ class MingwLinker(targetProperties: MingwConfigurables)
         return if (dir != null) "$dir/lib/windows/libclang_rt.$libraryName-$targetSuffix.a" else null
     }
 
-    /**
-     * Handle to command that runs LLD -### (i.e. without actual linkage) with arguments from [finalLinkCommands].
-     */
-    var lldCompatibilityChecker: ((Command) -> Unit)? = null
-
     override fun finalLinkCommands(objectFiles: List<ObjectFile>, executable: ExecutableFile,
                                    libraries: List<String>, linkerArgs: List<String>,
                                    optimize: Boolean, debug: Boolean,
@@ -482,29 +477,11 @@ class MingwLinker(targetProperties: MingwConfigurables)
             +additionalArguments
         }
 
-        if (HostManager.hostIsMingw) {
-            lldCompatibilityChecker?.let { checkLldCompatibiity ->
-                // -### flag allows to avoid actual linkage process.
-                val konanCxaDemangleSymbol = when (target) {
-                    KonanTarget.MINGW_X64 -> "Konan_cxa_demangle"
-                    KonanTarget.MINGW_X86 -> "_Konan_cxa_demangle"
-                    else -> error("Unexpected target: $target")
-                }
-                val lldCommand = Command(linker).constructLinkerArguments(
-                        // Add -fuse-ld to the end of the list to override previous appearances.
-                        additionalArguments = listOf("-fuse-ld=$absoluteLldLocation", "-Wl,-###"),
-                        // LLD doesn't support defsym.
-                        skipDefaultArguments = listOf("-Wl,--defsym,__cxa_demangle=$konanCxaDemangleSymbol")
-                )
-                checkLldCompatibiity(lldCommand)
-            }
-        }
-
         return listOf(when {
             HostManager.hostIsMingw -> Command(linker)
             else -> Command("wine64", "$linker.exe")
         }.constructLinkerArguments(
-                additionalArguments = listOf("-fuse-ld=${absoluteTargetToolchain}/bin/ld.exe")
+                additionalArguments = listOf("-fuse-ld=$absoluteLldLocation")
         ))
     }
 }