ftrace: dynamic ftrace process only text section

The text section stays in memory without ever leaving. With the exception
of modules, but modules know how to handle that case. With the dynamic
ftrace tracer, we need to make sure that it does not try to modify code
that no longer exists. The only safe section is .text.

This patch changes the recordmcount script to only record the mcount calls
in the .text sections.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>