librustc: Remove the unused `llvm_insn_ctxt` from the stats

src/librustc/middle/trans/common.rs

@@ -135,7 +135,6 @@ pub struct Stats {
     n_inlines: Cell<uint>,
     n_closures: Cell<uint>,
     n_llvm_insns: Cell<uint>,
-    llvm_insn_ctxt: ~[~str],
     llvm_insns: HashMap<~str, uint>,
     fn_stats: ~[(~str, uint, uint)] // (ident, time-in-ms, llvm-instructions)
 }

src/librustc/middle/trans/context.rs

@@ -220,7 +220,6 @@ impl CrateContext {
                     n_inlines: Cell::new(0u),
                     n_closures: Cell::new(0u),
                     n_llvm_insns: Cell::new(0u),
-                    llvm_insn_ctxt: ~[],
                     llvm_insns: HashMap::new(),
                     fn_stats: ~[]
                   },