trace: [tcg] Define TCG tracing helper routines

Generates file "trace/generated-helpers.c" with TCG helper definitions to trace
events in guest code at execution time.

The helpers ('helper_trace_${event}_exec_proxy') cast the TCG-compatible native
argument types to their original types (as defined in "trace-events") and call
the tracing routine ('trace_${event}_exec').

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/.gitignore b/.gitignore
index da56d70..643b34b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 /trace/generated-events.h
 /trace/generated-events.c
 /trace/generated-helpers.h
+/trace/generated-helpers.c
 /trace/generated-ust-provider.h
 /trace/generated-ust.c
 /libcacard/trace/generated-tracers.c