BUILD: tools: fix a build warning on some 32-bit archs

BUILD: tools: fix a build warning on some 32-bit archs

Some recent versions of gcc apparently can detect that x >> 32 will not
work on a 32-bit architecture, but are failing to see that the code will
not be built since it's enclosed in "if (sizeof(LONG) > 4)" or equivalent.
Just shift right twice by 16 bits in this case, the compiler correctly
replaces it by a single 32-bit shift.

No backport is needed.