[CMake] Update CMake cache file for the Win-to-Arm cross toolchains. NFC. (#93363)

* allow configuration for the target specific compiler flags.
* allow lld linker for all linker outputs: shared, module and exe.
* allow configuration of libc++ ABI version.
* set MSVC runtime library to MultiThreadedDLL/MultiThreadedDebugDLL on
Windows build hosts.
* install UCRT libraries on Windows build hosts

Author: vvereschaka

clang/cmake/caches/CrossWinToARMLinux.cmake

@@ -89,6 +89,13 @@ endif()
 
 message(STATUS "Toolchain target to build: ${LLVM_TARGETS_TO_BUILD}")
 
+# Allow to override libc++ ABI version. Use 2 by default.
+if (NOT DEFINED LIBCXX_ABI_VERSION)
+  set(LIBCXX_ABI_VERSION 2)
+endif()
+
+message(STATUS "Toolchain's Libc++ ABI version: ${LIBCXX_ABI_VERSION}")
+
 if (NOT DEFINED CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE "Release" CACHE STRING "")
 endif()
@@ -109,8 +116,15 @@ set(CLANG_DEFAULT_OBJCOPY                   "llvm-objcopy" CACHE STRING "")
 set(CLANG_DEFAULT_RTLIB                     "compiler-rt" CACHE STRING "")
 set(CLANG_DEFAULT_UNWINDLIB                 "libunwind" CACHE STRING "")
 
-if(WIN32)
-  set(CMAKE_MSVC_RUNTIME_LIBRARY            "MultiThreaded" CACHE STRING "")
+if (NOT DEFINED CMAKE_MSVC_RUNTIME_LIBRARY AND WIN32)
+  #Note: Always specify MT DLL for the LLDB build configurations on Windows host.
+  if (CMAKE_BUILD_TYPE STREQUAL "Debug")
+    set(CMAKE_MSVC_RUNTIME_LIBRARY            "MultiThreadedDebugDLL" CACHE STRING "")
+  else()
+    set(CMAKE_MSVC_RUNTIME_LIBRARY            "MultiThreadedDLL" CACHE STRING "")
+  endif()
+  # Grab all ucrt/vcruntime related DLLs into the binary installation folder.
+  set(CMAKE_INSTALL_UCRT_LIBRARIES          ON CACHE BOOL "")
 endif()
 
 # Set up RPATH for the target runtime/builtin libraries.
@@ -127,6 +141,15 @@ set(BUILTINS_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_INSTALL_RPATH
 set(BUILTINS_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_BUILD_WITH_INSTALL_RPATH            ON  CACHE BOOL "")
 set(BUILTINS_${TOOLCHAIN_TARGET_TRIPLE}_LLVM_CMAKE_DIR                            "${LLVM_PROJECT_DIR}/llvm/cmake/modules" CACHE PATH "")
 
+if (DEFINED TOOLCHAIN_TARGET_COMPILER_FLAGS)
+  foreach(lang C;CXX;ASM)
+    set(BUILTINS_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_${lang}_FLAGS         "${TOOLCHAIN_TARGET_COMPILER_FLAGS}" CACHE STRING "")
+  endforeach()
+endif()
+foreach(type SHARED;MODULE;EXE)
+  set(BUILTINS_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_${type}_LINKER_FLAGS    "-fuse-ld=lld" CACHE STRING "")
+endforeach()
+
 set(LLVM_RUNTIME_TARGETS                    "${TOOLCHAIN_TARGET_TRIPLE}" CACHE STRING "")
 set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR      ON CACHE BOOL "")
 
@@ -137,6 +160,15 @@ set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_SYSROOT
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_INSTALL_RPATH                       "${RUNTIMES_INSTALL_RPATH}"  CACHE STRING "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_BUILD_WITH_INSTALL_RPATH            ON  CACHE BOOL "")
 
+if (DEFINED TOOLCHAIN_TARGET_COMPILER_FLAGS)
+  foreach(lang C;CXX;ASM)
+    set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_${lang}_FLAGS         "${TOOLCHAIN_TARGET_COMPILER_FLAGS}" CACHE STRING "")
+  endforeach()
+endif()
+foreach(type SHARED;MODULE;EXE)
+  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_CMAKE_${type}_LINKER_FLAGS    "-fuse-ld=lld" CACHE STRING "")
+endforeach()
+
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_BUILD_BUILTINS                ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_BUILD_SANITIZERS              OFF CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_BUILD_XRAY                    OFF CACHE BOOL "")
@@ -164,7 +196,7 @@ set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_ENABLE_SHARED
 
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_USE_COMPILER_RT                    ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_SHARED                      OFF CACHE BOOL "")
-set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ABI_VERSION                        2 CACHE STRING "")
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ABI_VERSION                        ${LIBCXX_ABI_VERSION} CACHE STRING "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_CXX_ABI                            "libcxxabi" CACHE STRING "")    #!!!
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS      ON CACHE BOOL "")