The ec5761e cset introduced the symfs feature with a bug for loading vmlinux
files that ended up causing this failure:
[root@emilia v2.6.38-rc5+]# strace -e trace=open perf top --vmlinux ./vmlinux 2>&1 | tail -3
open("/./vmlinux", O_RDONLY) = -1 ENOENT (No such file or directory)
./vmlinux with build id b9266bf40e98dadb5d43a2f3e95d3c5d4aff46dc not found, continuing without symbols
The ./vmlinux file can't be used
[root@emilia v2.6.38-rc5+]#
Remove the extra slash, just like is done in the DSO__ORIG_DSO handling in
dso__load() and other parts of the ec5761e cset.