Bug: duplicate marker entry in Modules.marker

[Wenji Huang]

Hi Mathieu,

When I use marker in 2.6.25-rc5, found there could be duplicate marker 
entries in Modules.marker.

It can be reproduced through these steps:
     1. define trace_mark(mark1, "format 1, %d",var1). There is the 
entry in Modules.marker.
		mark1 vmlinux format 1, %d
     2. build and boot the kernel
     3. modify the marker, such as trace_mark(mark1, "format 2, 
%d",var1). There are two entries:
		mark1 vmlinux format 1, %d
		mark1 vmlinux format 2, %d

Although marker supports multi handlers, the only one marker is defined 
in kernel and stap script kernel.mark("mark1")
will be triggered two times.

Best regards,
Wenji