Fix the build on RHEL-9. (#98)

* Fix the build on RHEL-9.

It turns out that in the older version of lttng-ust on RHEL-9,
the API to set a marker is spelled _lttng_ust_tracef.  Include
the correct version header file, and use the correct API called
depending on what version we are using.

Signed-off-by: Chris Lalancette <[email protected]>
Co-authored-by: Tomoya Fujita <[email protected]>

Author: clalancette

test_tracetools/src/mark_process.cpp

@@ -14,6 +14,7 @@
 
 #ifndef TRACETOOLS_DISABLED
 #include <lttng/tracef.h>
+#include <lttng/ust-version.h>
 
 #include "rcpputils/env.hpp"
 #endif  // TRACETOOLS_DISABLED
@@ -40,7 +41,11 @@ void mark_trace_test_process()
   const std::string env_var{trace_test_id_env_var};
   const auto test_id = rcpputils::get_env_var(env_var.c_str());
   if (!test_id.empty()) {
+#if LTTNG_UST_MINOR_VERSION <= 12
+    _lttng_ust_tracef("%s=%s", env_var.c_str(), test_id.c_str());
+#else
     lttng_ust__tracef("%s=%s", env_var.c_str(), test_id.c_str());
+#endif
   }
 #endif  // TRACETOOLS_DISABLED
 }