Add missing space between errorprone flags

A space was missing between flags in the errorprone build rule.

Test: m -j RUN_ERROR_PRONE=true checkbuild
Change-Id: If6f48a700e6f19e318b6cc9734e1d8fd2289491f

java/builder.go

@@ -53,7 +53,7 @@ var (
 	errorprone = pctx.AndroidStaticRule("errorprone",
 		blueprint.RuleParams{
 			Command: `rm -rf "$outDir" "$annoDir" && mkdir -p "$outDir" "$annoDir" && ` +
-				`${config.ErrorProneCmd}` +
+				`${config.ErrorProneCmd} ` +
 				`$javacFlags $bootClasspath $classpath ` +
 				`-source $javaVersion -target $javaVersion ` +
 				`-d $outDir -s $annoDir @$out.rsp && ` +