MSVC documentation states: "This warning can be caused when a pointer to
a const or volatile item is assigned to a pointer not declared as
pointing to const or volatile."

Unfortunately, this happens when we dynamically allocate and deallocate
block of atomic variables using isc_mem_get and isc_mem_put.

Couple of examples:

  lib\isc\hp.c(134): warning C4090: 'function': different 'volatile' qualifiers [C:\builds\isc-projects\bind9\lib\isc\win32\libisc.vcxproj]
  lib\isc\hp.c(144): warning C4090: 'function': different 'volatile' qualifiers [C:\builds\isc-projects\bind9\lib\isc\win32\libisc.vcxproj]
  lib\isc\stats.c(55): warning C4090: 'function': different 'volatile' qualifiers [C:\builds\isc-projects\bind9\lib\isc\win32\libisc.vcxproj]
  lib\isc\stats.c(87): warning C4090: 'function': different 'volatile' qualifiers [C:\builds\isc-projects\bind9\lib\isc\win32\libisc.vcxproj]