BUILD: trace: include tools.h

If the TRACE option is used when compiling the haproxy source,
the following error occurs on debian 9.13:

src/calltrace.o: In function `make_line':
.../src/calltrace.c:204: undefined reference to `rdtsc'
src/calltrace.o: In function `calltrace':
.../src/calltrace.c:277: undefined reference to `rdtsc'
collect2: error: ld returned 1 exit status
Makefile:866: recipe for target 'haproxy' failed

src/calltrace.c

@@ -49,6 +49,7 @@
 #include <string.h>
 #include <haproxy/api.h>
 #include <haproxy/time.h>
+#include <haproxy/tools.h>
 
 static FILE *log;
 static int level;