Switch to sysprof-capture-4 unconditionally to avoid issues when
dev-libs/glib[static-libs] is present, which resulted in all of gtk+
static linking glib instead of dynamic linking.
Move the sysprof-capture to DEPEND-only, as the meson port hand-rolled
pkg-config file generation avoids putting sysprof-capture into
Requires.private section like autotools did when profiling was enabled.
Signed-off-by: Mart Raudsepp <leio@gentoo.org>