Also, make the analogous change to apple/swift-driver#1372, which gets the
sanitizer tests working on Android again, and remove the lld_lto feature in the
tests, which is now unused.
Fixes#60406
Ran the linux x86_64 compiler validation suite on this pull with `-use-ld=lld -Xlinker --gc-sections`, then without stripping as in the linked issue, and only saw the 20 unrelated failures just like @drodriguez had.
This commit adds LTO support for handling linker options and LLVM BC
emission. Even for ELF, swift-autolink-extract is unnecessary because
linker options are embeded in LLVM BC content when LTO.
This commit adds -lto flag for driver to enable LTO at LLVM level.
When -lto=llvm given, compiler emits LLVM bitcode file instead of object
file and perform thin LTO using libLTO.dylib plugin.
When -lto=llvm-full given, perform full LTO instead of thin LTO.
