cmake: Add systemtap-sdt optional package support

CMakeLists.txt

@@ -133,6 +133,11 @@ if(WITH_ZMQ)
   endif()
 endif()
 
+option(WITH_USDT "Enable tracepoints for Userspace, Statically Defined Tracing." OFF)
+if(WITH_USDT)
+  find_package(USDT MODULE REQUIRED)
+endif()
+
 set(configure_warnings)
 
 include(CheckPIESupported)
@@ -309,6 +314,7 @@ message("  port mapping:")
 message("   - using NAT-PMP .................... ${WITH_NATPMP}")
 message("   - using UPnP ....................... ${WITH_MINIUPNPC}")
 message("  ZeroMQ .............................. ${WITH_ZMQ}")
+message("  USDT tracing ........................ ${WITH_USDT}")
 message("Tests:")
 message("  test_bitcoin ........................ ${BUILD_TESTS}")
 message("")