dev-util/sysprof-capture: initial split from dev-util/sysprof

dev-util/sysprof-capture: initial split from dev-util/sysprof

Now with sysprof-capture-3.pc API, other GNOME components start to
more widely make use of providing their own capture data, for which
they use this sysprof-capture static library helper. This includes
x11-libs/gtk+, which would be an out of the box circular dependency
if sysprof-capture is kept as part of full dev-util/sysprof package.
Add a split package as really intended, which gtk+, mutter and
others can DEPEND on (but don't need to RDEPEND), probably even
by default.

Package-Manager: Portage-2.3.84, Repoman-2.3.20
Signed-off-by: Mart Raudsepp <leio@gentoo.org>