This change enables lldb-platform for Linux. In addition, it does the following:
* fixes Host::GetLLDBPath() to work on Linux/*BSD for ePathTypeSupportExecutableDir-relative paths.
* adds more logging and comments around lldb-platform startup and remote lldb-platform usage.
* refactors lldb-platform remote-* support for Darwin and Linux into PlatformPOSIX. This, in theory, is the bulk of what is needed for *BSD to make remote connections to lldb-platform as well (although I haven't tested that yet). FreeBSD can make similar changes to their Platform* as was made here for PlatformLinux to pick up the rest of the bits.
* teaches GDBRemoteCommunication to use lldb-gdbserver for non-Apple hosts.
llvm-svn: 213707
015d818b59