Update XRay to support x86-64 (RDTSC), use dladdr() as an optional way to

native_client_sdk/src/libraries/xray/library.dsc

 {
   'TOOLS': ['newlib', 'glibc'],
   'SEARCH': [
     '.'
   ],
   'TARGETS': [
     {
       'NAME' : 'xray',
       'TYPE' : 'lib',
       'SOURCES' : [
         'hashtable.c',
         'stringpool.c',
         'symtable.c',
         'xray.c'
       ],
       'CCFLAGS': [      
-        '-DXRAY -O2'    
+        '-DXRAY -DXRAY_ANNOTATE -O2'
       ]
     }
   ],
   'HEADERS': [
     {
       'FILES': [
         'xray.h',
         'xray_priv.h'
       ],
       'DEST': 'include/xray',
     }
   ],
   'DEST': 'src',
   'NAME': 'xray',
   'EXPERIMENTAL': True,
 }