[llvm] Include LLVM_ENABLE_RUNTIMES in the cross compilation invocation

[JDevlieghere]

Summary

Forward the LLVM_ENABLE_RUNTIMES cmake variable in the cross compilation invocation.

Now that passing libcxx must be specified in LLVM_ENABLE_RUNTIMES instead of LLVM_ENABLE_PROJECTS, the LLDB's sanity check for libcxx trips up (in the cross compilation case) because the runtimes are not forwarded. This patch fixes that.

[JDevlieghere]

Without this change, you get something like:

[551/5308] Configuring NATIVE LLVM...
FAILED: NATIVE/CMakeCache.txt /Users/jonas/llvm/build-ra/NATIVE/CMakeCache.txt
...
CMake Error at /Users/jonas/llvm/llvm-project/lldb/test/CMakeLists.txt:122 (message):
  LLDB test suite requires libc++, but it is currently disabled.  Please add
  `libcxx` to `LLVM_ENABLE_RUNTIMES`, or disable tests via
  `LLDB_INCLUDE_TESTS=OFF`.

I'm putting up a separate patch to specify only LLVM_ENABLE_RUNTIMES in the error message.

edit: D112856

[smeenai]

LGTM, thanks.

llvm/cmake/modules/CrossCompile.cmake

string(REPLACE ";" "$<SEMICOLON>" targets_to_build_arg
          "${LLVM_TARGETS_TO_BUILD}")
   string(REPLACE ";" "$<SEMICOLON>" experimental_targets_to_build_arg
          "${LLVM_EXPERIMENTAL_TARGETS_TO_BUILD}")
 
   string(REPLACE ";" "$<SEMICOLON>" llvm_enable_projects_arg
          "${LLVM_ENABLE_PROJECTS}")
   string(REPLACE ";" "$<SEMICOLON>" llvm_external_projects_arg
          "${LLVM_EXTERNAL_PROJECTS}")
+  string(REPLACE ";" "$<SEMICOLON>" llvm_enable_runtimes_arg
+         "${LLVM_ENABLE_RUNTIMES}")
 
   set(external_project_source_dirs)
   foreach(project ${LLVM_EXTERNAL_PROJECTS})
     canonicalize_tool_name(${project} name)
     list(APPEND external_project_source_dirs
          "-DLLVM_EXTERNAL_${name}_SOURCE_DIR=${LLVM_EXTERNAL_${name}_SOURCE_DIR}")
   endforeach()
 
   add_custom_command(OUTPUT ${${project_name}_${target_name}_BUILD}/CMakeCache.txt
     COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}"
         -DCMAKE_MAKE_PROGRAM="${CMAKE_MAKE_PROGRAM}"
         ${CROSS_TOOLCHAIN_FLAGS_${target_name}} ${CMAKE_CURRENT_SOURCE_DIR}
         ${CROSS_TOOLCHAIN_FLAGS_${project_name}_${target_name}}
         -DLLVM_TARGET_IS_CROSSCOMPILE_HOST=TRUE
         -DLLVM_TARGETS_TO_BUILD="${targets_to_build_arg}"
         -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="${experimental_targets_to_build_arg}"
         -DLLVM_DEFAULT_TARGET_TRIPLE="${TARGET_TRIPLE}"
         -DLLVM_TARGET_ARCH="${LLVM_TARGET_ARCH}"
         -DLLVM_ENABLE_PROJECTS="${llvm_enable_projects_arg}"
         -DLLVM_EXTERNAL_PROJECTS="${llvm_external_projects_arg}"
+        -DLLVM_ENABLE_RUNTIMES="${llvm_enable_runtimes_arg}"
         ${external_project_source_dirs}
         -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN="${LLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN}"
         ${build_type_flags} ${linker_flag} ${external_clang_dir}
         ${ARGN}
     WORKING_DIRECTORY ${${project_name}_${target_name}_BUILD}
     DEPENDS CREATE_${project_name}_${target_name}
     COMMENT "Configuring ${target_name} ${project_name}...")