Add StructuredData plugin type; showcase with new DarwinLog feature

Take 2, with missing cmake line fixed.  Build tested on
Ubuntu 14.04 with clang-3.6.

See docs/structured_data/StructuredDataPlugins.md for details.

differential review: https://reviews.llvm.org/D22976

reviewers: clayborg, jingham
llvm-svn: 279202
diff --git a/lldb/tools/debugserver/source/DNB.h b/lldb/tools/debugserver/source/DNB.h
index fbaf5e3..3e928e6 100644
--- a/lldb/tools/debugserver/source/DNB.h
+++ b/lldb/tools/debugserver/source/DNB.h
@@ -14,6 +14,7 @@
 #ifndef __DNB_h__
 #define __DNB_h__
 
+#include "MacOSX/DarwinLog/DarwinLogEvent.h"
 #include "MacOSX/Genealogy.h"
 #include "MacOSX/ThreadInfo.h"
 #include "JSONGenerator.h"
@@ -81,6 +82,8 @@
 int             DNBProcessMemoryRegionInfo  (nub_process_t pid, nub_addr_t addr, DNBRegionInfo *region_info) DNB_EXPORT;
 std::string     DNBProcessGetProfileData (nub_process_t pid, DNBProfileDataScanType scanType) DNB_EXPORT;
 nub_bool_t      DNBProcessSetEnableAsyncProfiling   (nub_process_t pid, nub_bool_t enable, uint64_t interval_usec, DNBProfileDataScanType scan_type) DNB_EXPORT;
+DarwinLogEventVector DNBProcessGetAvailableDarwinLogEvents(nub_process_t pid);
+
 
 //----------------------------------------------------------------------
 // Process status