[LLD] Set alignment as part of Characteristics in TLS table.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46473

LLD wasn't previously specifying any specific alignment in the TLS table's Characteristics field so the loader would just assume the default value (16 bytes). This works most of the time except if you have thread locals that want specific higher alignments (e.g. 32 as in the bug) *even* if they specify an alignment on the thread local. This change updates LLD to take the max alignment from tls section.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D88637