Make llvm::crc32() work also for input sizes larger than 32 bits.

The problem was noticed by the Chrome OS toolchain folks
(crbug.com/1048445) because llvm-objcopy --add-gnu-debuglink would
insert the wrong checksum when processing a binary larger than 4 GB.
That use case regressed in 1e1e3ba2 when we started using
llvm::crc32() in more places.

Differential revision: https://reviews.llvm.org/D74039

(cherry picked from commit 6c4a8bc0)