perf probe: Fix strtailcmp() to compare s1and s2[0]

Fix strtailcmp() to compare s1[0] and s2[0]. strtailcmp() returns 0
if "a" and "b" or "a" and "ab", it's a wrong behavior. This patch
fixes it.

Signed-off-by: "Juha Leppanen" <juha_motorsportcom@luukku.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Juha Leppanen <juha_motorsportcom@luukku.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091207170040.19230.37464.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>