Support b_lto with clang-cl and lld-link

[Helyos96]

Describe the bug When using clang-cl and lld-link, b_lto is not recognized by meson.

$ meson configure -Db_lto=true

ERROR: Unknown options: "b_lto"

Expected behavior clang-cl and lld-link supporting link-time optimization, meson should be able to plug it in too.

system parameters

• Windows 11, using CC=clang-cl; CXX=clang-cl (lld-link is set as the default linker)
• Python 3.11.2
• meson 1.4.0

[dcbaker]

We support this for the gcc style clang, so adding it to clang-cl should be pretty easy if someone was looking for a good first project on windows.