util: Make virStringStripSuffix() return bool

util: Make virStringStripSuffix() return bool

While this function is not, strictly speaking, a predicate,
it still mostly behaves like one as evidenced by the vast
majority of its callers, so using bool rather than int as
the return type makes sense.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
ACKed-by: Peter Krempa <pkrempa@redhat.com>