interp: improve error reporting

This commit improves error reporting in several ways:

  * Location information is read from the intruction that causes the
    error, as far as that's available.
  * The package that is being interpreted is included in the error
    message. This may be the most useful part of the improvements.
  * The hashmap update intrinsics now doesn't panic, instead it logs a
    clear error (with location information, as in the above two bullet
    points).

This is possible thanks to improvements in LLVM 9. This means that after
this change, TinyGo will depend on LLVM 9.

main.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"go/scanner"
 	"go/types"
 	"io"
 	"os"
@@ -480,11 +481,21 @@ func handleCompilerError(err error) {
 		switch err := err.(type) {
 		case *interp.Unsupported:
 			// hit an unknown/unsupported instruction
-			fmt.Fprintln(os.Stderr, "unsupported instruction during init evaluation:")
+			fmt.Fprintln(os.Stderr, "#", err.ImportPath)
+			msg := "unsupported instruction during init evaluation:"
+			if err.Pos.String() != "" {
+				msg = err.Pos.String() + " " + msg
+			}
+			fmt.Fprintln(os.Stderr, msg)
 			err.Inst.Dump()
 			fmt.Fprintln(os.Stderr)
-		case types.Error:
+		case types.Error, scanner.Error:
 			fmt.Fprintln(os.Stderr, err)
+		case interp.Error:
+			fmt.Fprintln(os.Stderr, "#", err.ImportPath)
+			for _, err := range err.Errs {
+				fmt.Fprintln(os.Stderr, err)
+			}
 		case loader.Errors:
 			fmt.Fprintln(os.Stderr, "#", err.Pkg.ImportPath)
 			for _, err := range err.Errs {