LLVM_TOOLS: Include llvm-link as a llvm tool

src/bootstrap/src/lib.rs

@@ -64,6 +64,7 @@
     "llvm-ar",       // used for creating and modifying archive files
     "llvm-as",       // used to convert LLVM assembly to LLVM bitcode
     "llvm-dis",      // used to disassemble LLVM bitcode
+    "llvm-link",     // Used to link LLVM bitcode
     "llc",           // used to compile LLVM bytecode
     "opt",           // used to optimize LLVM bytecode
 ];