trace-tools: use ifdef to check CXXABI

As documented here:
https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Generic-Headers.html

Change-Id: I58775858404d1f3eab7ea1cd87acf0bee94e1533

src/jami/trace-tools.h

@@ -32,7 +32,7 @@
 #  define CURRENT_LINE()     0
 #endif
 
-#if HAVE_CXXABI_H
+#ifdef HAVE_CXXABI_H
 #include <cxxabi.h>
 
 template<typename T>