Only emit the section sym if we're emitting the section.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189288 91177308-0d34-0410-b5e6-96231b3b80d8
Treat the pubtypes section similarly to the pubnames section and emit
it by default under linux or when we're trying to keep compatibility
with old gdb versions.

Fix testcase for option name change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189289 91177308-0d34-0410-b5e6-96231b3b80d8