dev-cpp/folly: install cmake files in the correct libdir

All Facebook packages unconditionally install libraries to PREFIX/lib,
which triggers multilib checks. The checks don't trigger for stuff like
CMake files though, so this was missed. This matches the other Facebook
packages like Watchman and its dependencies.

Signed-off-by: sin-ack <sin-ack@protonmail.com>
Signed-off-by: Sam James <sam@gentoo.org>

dev-cpp/folly/folly-2024.11.04.00-r2.ebuild

@@ -67,6 +67,7 @@ src_unpack() {
 src_configure() {
 	# TODO: liburing could in theory be optional but fails to link
 	local mycmakeargs=(
+		-DCMAKE_INSTALL_DIR="$(get_libdir)/cmake/${PN}"
 		-DLIB_INSTALL_DIR="$(get_libdir)"
 
 		-DBUILD_TESTS=$(usex test)