[ffigen] Code cleanup (#496)

pkgs/ffigen/lib/src/header_parser/parser.dart

diff --git a/pkgs/ffigen/lib/src/header_parser/parser.dart b/pkgs/ffigen/lib/src/header_parser/parser.dart
index b45b062..871da44 100644
--- a/pkgs/ffigen/lib/src/header_parser/parser.dart
+++ b/pkgs/ffigen/lib/src/header_parser/parser.dart
@@ -56,24 +56,21 @@
   final index = clang.clang_createIndex(0, 0);
 
   Pointer<Pointer<Utf8>> clangCmdArgs = nullptr;
-  final compilerOpts = <String>[];
+  final compilerOpts = <String>[
+    // Add compiler opt for comment parsing for clang based on config.
+    if (config.commentType.length != CommentLength.none &&
+        config.commentType.style == CommentStyle.any)
+      strings.fparseAllComments,
 
-  // Add compiler opt for comment parsing for clang based on config.
-  if (config.commentType.length != CommentLength.none &&
-      config.commentType.style == CommentStyle.any) {
-    compilerOpts.add(strings.fparseAllComments);
-  }
-
-  // If the config targets Objective C, add a compiler opt for it.
-  if (config.language == Language.objc) {
-    compilerOpts.addAll([
+    // If the config targets Objective C, add a compiler opt for it.
+    if (config.language == Language.objc) ...[
       ...strings.clangLangObjC,
       ..._findObjectiveCSysroot(),
-    ]);
-  }
+    ],
 
-  // Add the user options last so they can override any other options.
-  compilerOpts.addAll(config.compilerOpts);
+    // Add the user options last so they can override any other options.
+    ...config.compilerOpts
+  ];
 
   _logger.fine('CompilerOpts used: $compilerOpts');
   clangCmdArgs = createDynamicStringArray(compilerOpts);