scripts/decode_stacktrace: only strip base path when a prefix of the path

scripts/decode_stacktrace: only strip base path when a prefix of the path

Running something like:

	decodecode vmlinux .

leads to interested results where not only the leading "." gets stripped
from the displayed paths, but also anywhere in the string, displaying
something like:

	kvm_vcpu_check_block (arch/arm64/kvm/virt/kvm/kvm_mainc:2141)

which doesn't help further processing.

Fix it by only stripping the base path if it is a prefix of the path.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Marc Zyngier <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>