elf-core: Document offset constants in FreeBSD prstatus parser

Also accomodate struct padding based on arch, for later i386 work.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187040 91177308-0d34-0410-b5e6-96231b3b80d8
Add FreeBSD buildbots to build page


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187043 91177308-0d34-0410-b5e6-96231b3b80d8
Update www build instructions for FreeBSD



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187045 91177308-0d34-0410-b5e6-96231b3b80d8