Auto merge of #22530 - rprichard:master, r=dotdash

Fixes #22525

I wasn't sure if I should reuse `write::get_llvm_opt_level` or not.  It returns an `llvm::CodeGenOptLevel`, which is the Rust binding for `CodeGenOpt::Level`. `lto.rs` is passing an optlevel to LLVM's `PassManagerBuilder`, which takes an unsigned int.  `PassManagerBuilder`'s optlevel uses essentially the same enumeration (i.e. 0-3 with 2 as default), but it's implicit.

src/librustc_trans/back/lto.rs

@@ -167,7 +167,12 @@ pub fn run(sess: &session::Session, llmod: ModuleRef,
         llvm::LLVMRustAddAnalysisPasses(tm, pm, llmod);
         llvm::LLVMRustAddPass(pm, "verify\0".as_ptr() as *const _);
 
-        let opt = sess.opts.cg.opt_level.unwrap_or(0) as libc::c_uint;
+        let opt = match sess.opts.optimize {
+            config::No => 0,
+            config::Less => 1,
+            config::Default => 2,
+            config::Aggressive => 3,
+        };
 
         let builder = llvm::LLVMPassManagerBuilderCreate();
         llvm::LLVMPassManagerBuilderSetOptLevel(builder, opt);

src/test/run-pass/sepcomp-lib-lto.rs

@@ -14,6 +14,7 @@
 // aux-build:sepcomp_lib.rs
 // compile-flags: -C lto
 // no-prefer-dynamic
+// ignore-android FIXME #18800
 
 extern crate sepcomp_lib;
 use sepcomp_lib::a::one;