[libunwind] [CMake] Remove leftover no-op cmake variable setting. NFC.

[mstorsjo]

Summary

The setting and restoring of this variable became unused in
3ee0cec88effc88285732c8bec2a8f0e4e37c0b1 / D112155.

libunwind/CMakeLists.txt

 
 # Include macros for adding and removing libunwind flags.
 include(HandleLibunwindFlags)
 
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
-# Compiler tests may be failing if the compiler implicitly links in libunwind,
-# which doesn't exist yet. This gets waived by --unwindlib=none
-# later in config-ix below, but the tests for --target etc before that may
-# be failing due to it. Only test compilation, not linking, for these
-# tests here now.
-set(CMAKE_TRY_COMPILE_TARGET_TYPE_ORIG ${CMAKE_TRY_COMPILE_TARGET_TYPE})
-set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
-set(CMAKE_TRY_COMPILE_TARGET_TYPE ${CMAKE_TRY_COMPILE_TARGET_TYPE_ORIG})
-
 # Configure compiler.
 include(config-ix)
 
 if (LIBUNWIND_USE_COMPILER_RT AND NOT LIBUNWIND_HAS_NODEFAULTLIBS_FLAG)
   list(APPEND LIBUNWIND_LINK_FLAGS "-rtlib=compiler-rt")
 endif()
 
 add_compile_flags_if_supported(-Werror=return-type)