[clang-doc] Bump BitcodeWriter max line number to 32U
[clang-doc] Bump BitcodeWriter max line number to 32U

PR43039 reports hitting the assert on a very large file, so bumping this
to allow for larger files.

Differential Revision: https://reviews.llvm.org/D66681

git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@369811 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra