[intel-pt] Fix building due to CMake + python changes

Python is now handled in CMake with different variables, thus
the intel plugin needs a corresponding update.

Test Plan:

Differential Revision: https://phabricator.intern.facebook.com/D22555992

lldb/tools/intel-features/CMakeLists.txt

@@ -56,7 +56,7 @@ add_lldb_library(lldbIntelFeatures SHARED
 
   LINK_LIBS
     ${FEATURE_LIBS}
-    ${PYTHON_LIBRARY}
+    ${PYTHON_LIBRARIES}
   )
 
 # Add link dependencies for python wrapper