Rearrange bitfield to allow for more space in file_idx.
Rearrange bitfield to allow for more space in file_idx.

This is an alternate patch for the bug reported in
https://bugs.llvm.org/show_bug.cgi?id=39816 ("lldb doesn't show a file
of line entry for big project"). This limits the number of lines in a
source file to 32M, which I think is reasonable even for preprocessed
source inputs.

Differential Revision: https://reviews.llvm.org/D56218

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@350274 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb