app-antivirus/clamav: add rust_pkg_setup

This does not cause any changes to package behaviour;
we don't depend on LLVM or have any version restrictions on
Rust so it doesn't matter which slot was picked - it's probably
the `eselect`ed one anyway.

There's no need to force a revbump on users who have already
built the package, however we can provide consistent selection
of dev-lang/rust via the eclass and get some output on the
selected slot as part of the build log if we fix this now.

Signed-off-by: Matt Jolly <kangie@gentoo.org>

app-antivirus/clamav/clamav-1.0.7-r1.ebuild

@@ -228,6 +228,7 @@ python_check_deps() {
 }
 
 pkg_setup() {
+	rust_pkg_setup
 	use jit && llvm_pkg_setup
 	use test && python-any-r1_pkg_setup
 }

app-antivirus/clamav/clamav-1.4.1-r2.ebuild

@@ -231,6 +231,7 @@ python_check_deps() {
 }
 
 pkg_setup() {
+	rust_pkg_setup
 	use jit && llvm_pkg_setup
 	use test && python-any-r1_pkg_setup
 }