When CONFIG_DYNAMIC_FTRACE is not set, ftrace_location() is not defined.
If a user (like kprobes) references this function, it will break
the compile when CONFIG_DYNAMIC_FTRACE is not set.

Add ftrace_location() as a nop (return 0) when DYNAMIC_FTRACE
is not defined.

Link: http://lkml.kernel.org/r/20120612225426.961092717@goodmis.orgSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>