perf build: Ensure libtraceevent and libtracefs versions have 3 components

When either of these have a shorter version, like 1.8, the expression
that computes the version has a syntax error that can be seen in the
output of make:

expr: syntax error: missing argument after +

Link: https://bugs.gentoo.org/917559


Reported-by: Peter Volkov <peter.volkov@gmail.com>
Signed-off-by: Guilherme Amadio <amadio@gentoo.org>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240606153625.2255470-3-amadio@gentoo.org