trace-cmd: Do not make trace-cmd have to build with ptrace

If ptrace is not available on an OS or arch, do not fail the build.
Simply do not support the child tracing feature.

Reported-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
1 file changed