[X86][BranchAlign] Suppress branch alignment for {,_}__tls_get_addr

The x86-64 General Dynamic TLS code sequence uses prefixes to allow
linker relaxation.  Adding segment override prefix or NOPs can break
linker relaxation (ld -pie/-no-pie).

i386 General Dynamic and x86-64 Local Dynamic do not use prefixes, but
for simplicity, just disable auto padding consistently.

Reviewed By: skan, LuoYuanke

Differential Revision: https://reviews.llvm.org/D72878