build: force falco version to always start with a digit
build: force falco version to always start with a digit

Falco version respects the following rules:
If the current commit matches (exactly) a git tag then the
FALCO_VERSION equals it (with the initial "v" stripped out).
Otherwise FALCO_VERSION is 0.<commit hash>[.-dirty].

Signed-off-by: Leonardo Di Donato <2012e0ca99d70aa6c893822ff73002216e5dba72@gmail.com>

draios/falco,draios/falco,draios/falco,draios/falco,draios/falco,draios/falco,draios/falco,draios/falco