This patch updates `SBCompileUnit::FindLineEntryIndex` to pass a valid
`LineEntry` pointer to `CompileUnit::FindLineEntry`.
This caused `LineTable::FindLineEntryIndexByFileIndexImpl` to return its
`best_match` initial value (UINT32_MAX).
rdar://78115426
Differential Revision: https://reviews.llvm.org/D102658
Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>