cmake HAVE_SDT_TRACEPOINT examples

Bitcoin-ABC/bitcoin-abc src/config/CMakeLists.txt :276

check_cxx_source_compiles("
	#include <sys/sdt.h>
	int main() {
		DTRACE_PROBE(\"context\", \"event\");
		return 0;
	}
	" HAVE_SDT_TRACEPOINT)