build: add package ID to compiler and optimization error messages

This improves error reporting slightly.

testdata/errors/compiler.go

@@ -7,7 +7,6 @@ func foo() {
 //go:align 7
 var global int
 
-// TODO: include package name in the error message
-
+// ERROR: # command-line-arguments
 // ERROR: compiler.go:4:6: can only use //go:wasmimport on declarations
 // ERROR: compiler.go:8:5: global variable alignment must be a positive power of two

testdata/errors/optimizer.go

@@ -14,5 +14,6 @@ func main() {
 	})
 }
 
+// ERROR: # command-line-arguments
 // ERROR: optimizer.go:9:15: interrupt ID is not a constant
 // ERROR: optimizer.go:13:15: interrupt ID is not a constant