Address Kou's comments Dec-16

Move `include(ThirdpartyToolchain)`

Author: alinaliBQ

cpp/CMakeLists.txt

@@ -520,8 +520,6 @@ endif()
 set(PARQUET_PC_REQUIRES "")
 set(PARQUET_PC_REQUIRES_PRIVATE "")
 
-include(ThirdpartyToolchain)
-
 # Add common flags
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CXX_COMMON_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${ARROW_CXXFLAGS}")
@@ -536,6 +534,8 @@ string(REPLACE "-std=c++17" "" CMAKE_C_FLAGS ${CMAKE_C_FLAGS})
 # Add C++-only flags, like -std=c++17
 set(CMAKE_CXX_FLAGS "${CXX_ONLY_FLAGS} ${CMAKE_CXX_FLAGS}")
 
+include(ThirdpartyToolchain)
+
 # ASAN / TSAN / UBSAN
 if(ARROW_FUZZING)
   set(ARROW_USE_COVERAGE ON)

cpp/cmake_modules/SetupCxxFlags.cmake

@@ -186,7 +186,6 @@ if(WIN32)
       #
       # ARROW-2986: Without /EHsc we get C4530 warning
       set(CXX_COMMON_FLAGS "/W3 /EHsc")
-      string(APPEND CMAKE_CXX_FLAGS " /EHsc")
     endif()
 
     # Disable C5105 (macro expansion producing 'defined' has undefined