Report error if OS is not 64-bit

CMakeLists.txt

@@ -413,3 +413,8 @@ target_link_libraries(rippled
   ${OPENSSL_LIBRARIES} ${PROTOBUF_LIBRARIES} ${SANITIZER_LIBRARIES})
 
 link_common_libraries(rippled)
+
+if (NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
+  message(WARNING "Rippled requires a 64 bit target architecture.\n"
+    "The most likely cause of this warning is trying to build rippled with a 32-bit OS.")
+endif()

SConstruct

@@ -115,6 +115,7 @@ TODO
 
 import collections
 import os
+import platform
 import subprocess
 import sys
 import textwrap
@@ -122,6 +123,10 @@ import time
 import glob
 import SCons.Action
 
+if (platform.architecture()[0] != '64bit'):
+    print('Warning: Detected {} architecture. Rippled requires a 64-bit OS.'.format(
+          platform.architecture()[0]));
+
 sys.path.append(os.path.join('src', 'ripple', 'beast', 'site_scons'))
 sys.path.append(os.path.join('src', 'ripple', 'site_scons'))