Revert SetupCxxFlags change

Author: amoeba

cpp/cmake_modules/SetupCxxFlags.cmake

@@ -49,11 +49,7 @@ endif()
 if(ARROW_CPU_FLAG STREQUAL "x86")
   # x86/amd64 compiler flags, msvc/gcc/clang
   if(MSVC)
-    set(ARROW_SSE4_2_FLAG "/arch:SSE4.2")
-    # These definitions are needed for xsimd to consider the corresponding instruction
-    # sets available, but they are not set by MSVC (unlike other compilers).
-    # See https://github.com/AcademySoftwareFoundation/OpenImageIO/issues/4265
-    add_definitions(-D__SSE2__ -D__SSE4_1__ -D__SSE4_2__)
+    set(ARROW_SSE4_2_FLAG "")
     set(ARROW_AVX2_FLAG "/arch:AVX2")
     # MSVC has no specific flag for BMI2, it seems to be enabled with AVX2
     set(ARROW_BMI2_FLAG "/arch:AVX2")