devel/rust-analyzer: mark as LTO_UNSAFE

rust-analyzer won't run (repeatedly terminated with signal 6) when
called from VSCode's rust-analyzer extension.

Error messages from rust-analyzer extension are as follows:
[Info  - 17:39:30] Connection to server got closed. Server will restart.
[Info  - 17:39:31] Connection to server got closed. Server will restart.
[Info  - 17:39:31] Connection to server got closed. Server will restart.
[Info  - 17:39:32] Connection to server got closed. Server will restart.
[Error - 17:39:32] The Rust Analyzer Language Server server crashed 5 times in the last 3 minutes. The server will not be restarted. See the output for more information.

Turning off LTO appears to work around the issue.

PR:		272291
Approved by:	mikael

devel/rust-analyzer/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	rust-analyzer
 DISTVERSION=	2023-06-12
+PORTREVISION=	1
 CATEGORIES=	devel
 
 MAINTAINER=	rust@FreeBSD.org
@@ -203,6 +204,8 @@ CARGO_CRATES=	addr2line-0.19.0 \
 
 CARGO_INSTALL_PATH=	crates/rust-analyzer
 
+LTO_UNSAFE=	yes
+
 # attempts to install rustup toolchains
 NO_TEST=	yes