Use CMAKE_SIZEOF_VOID_P instead of CMAKE_CL_64

CMake's documentation says this is preferred.
https://cmake.org/cmake/help/latest/variable/CMAKE_CL_64.html

Reportedly, it also works better with MINGW, though we do not currently
support MINGW with the CMake build. See
https://boringssl-review.googlesource.com/c/boringssl/+/41704/

Change-Id: Ie5794306beeeff816b34ee98c7a0f8e0d4f99ec8
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/41724
Reviewed-by: Adam Langley <[email protected]>
Commit-Queue: David Benjamin <[email protected]>

Author: davidben

CMakeLists.txt

@@ -471,7 +471,7 @@ elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "amd64")
   set(ARCH "x86_64")
 elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "AMD64")
   # cmake reports AMD64 on Windows, but we might be building for 32-bit.
-  if(CMAKE_CL_64)
+  if(CMAKE_SIZEOF_VOID_P EQUAL 8)
     set(ARCH "x86_64")
   else()
     set(ARCH "x86")

util/generate_build_files.py

@@ -489,7 +489,7 @@ def __init__(self):
   set(ARCH "x86_64")
 elseif(${CMAKE_SYSTEM_PROCESSOR} STREQUAL "AMD64")
   # cmake reports AMD64 on Windows, but we might be building for 32-bit.
-  if(CMAKE_CL_64)
+  if(CMAKE_SIZEOF_VOID_P EQUAL 8)
     set(ARCH "x86_64")
   else()
     set(ARCH "x86")