Don't dereference target if it is NULL. 

Caught by the clang static analyzer by Jason Molenda.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@210941 91177308-0d34-0410-b5e6-96231b3b80d8
Add a check that we found an ABI plugin before calling a method on it.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@210942 91177308-0d34-0410-b5e6-96231b3b80d8
Add documentation about the jThreadExtendedInfo packet.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@210949 91177308-0d34-0410-b5e6-96231b3b80d8