Fix #426

src/dfmt/formatter.d

@@ -716,6 +716,7 @@ private:
         }
         else if (index < tokens.length && (currentIs(tok!"@")
                 || isBasicType(tokens[index].type)
+                || currentIs(tok!"extern")
                 || currentIs(tok!"identifier"))
                 && !currentIsIndentedTemplateConstraint())
             write(" ");

tests/allman/issue0426.d.ref

@@ -0,0 +1,6 @@
+import std.stdio;
+
+@safe extern (C) void main()
+{
+    writeln("Hello World!");
+}

tests/issue0426.d

@@ -0,0 +1,5 @@
+import std.stdio;
+
+@safe extern(C) void main() {
+    writeln("Hello World!");
+}

tests/otbs/issue0426.d.ref

@@ -0,0 +1,5 @@
+import std.stdio;
+
+@safe extern (C) void main() {
+    writeln("Hello World!");
+}