[CMake][libunwind] Fix the -target and -gcc-toolchain flag handling

[phosek]

Summary

CMake has the problem with the single dash variant because of the space, so use the double dash with equal sign version. The compile flag handling had a typo which caused these flag not to be properly include. We also don't have to pass the target triple when checking for compiler-rt since that flag is already included in compile flags now.

[compnerd]

CMakeLists.txt

190

I think that the space is easily worked with. We just need to append two items instead of one so that the quoting is handled properly. I do really prefer the single dash version for the -target flag.

CMakeLists.txt

if (${condition})
     list(APPEND ${list} ${var})
   endif()
 endmacro()
 
 macro(add_target_flags_if condition var)
   if (${condition})
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${var}")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${var}")
-    list(APPEND LINUNWIND_COMPILE_FLAGS ${var})
+    list(APPEND LIBUNWIND_COMPILE_FLAGS ${var})
     list(APPEND LIBUNWIND_LINK_FLAGS ${var})
   endif()
 endmacro()
 
 add_target_flags_if(LIBUNWIND_BUILD_32_BITS "-m32")
 add_target_flags_if(LIBUNWIND_TARGET_TRIPLE
-          "-target ${LIBUNWIND_TARGET_TRIPLE}")
+          "--target=${LIBUNWIND_TARGET_TRIPLE}")
 add_target_flags_if(LIBUNWIND_GCC_TOOLCHAIN
-          "-gcc-toolchain ${LIBUNWIND_GCC_TOOLCHAIN}")
+          "--gcc-toolchain=${LIBUNWIND_GCC_TOOLCHAIN}")
 add_target_flags_if(LIBUNWIND_SYSROOT
           "--sysroot=${LIBUNWIND_SYSROOT}")
 
 # Configure compiler.
 include(config-ix)
 
 if (LIBUNWIND_USE_COMPILER_RT)
   list(APPEND LIBUNWIND_LINK_FLAGS "-rtlib=compiler-rt")

cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name dest)
   if (NOT DEFINED LIBUNWIND_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBUNWIND_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
-  set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${TARGET_TRIPLE} ${LIBUNWIND_COMPILE_FLAGS}
+  set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBUNWIND_COMPILE_FLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE