'unnamed' bss section, but some impls would want a named one. Since
they don't have consistent behavior, just make each target do their
own thing, instead of doing something "sortof common" then having
targets change immutable objects later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77165 91177308-0d34-0410-b5e6-96231b3b80d8
1. Spell SectionFlags::Writeable as "Writable".
2. Add predicates for deriving SectionFlags from SectionKinds.
3. Sink ELF-specific getSectionPrefixForUniqueGlobal impl into
ELFTargetAsmInfo.
4. Fix SectionFlagsForGlobal to know that BSS/ThreadBSS has the
BSS bit set (the real fix for PR4619).
5. Fix isSuitableForBSS to not put globals with explicit sections
set in BSS (which was the reason #4 wasn't fixed earlier).
6. Remove my previous hack for PR4619.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77085 91177308-0d34-0410-b5e6-96231b3b80d8
