[libadwaita] hacking: Drop redundant empty lines

[Alexander Mikhaylenko <alexm src gnome org>]

commit 2baf0f389c638a09fb668e601ee03304aa645633
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Tue May 25 13:55:09 2021 +0200

    hacking: Drop redundant empty lines

 HACKING.md | 6 ------
 1 file changed, 6 deletions(-)
---
diff --git a/HACKING.md b/HACKING.md
index d4f627c3..ef3dd7b8 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -48,7 +48,6 @@ static gboolean
 key_press_event_cb (GtkWidget *widget, GdkEvent *event, gpointer data)
 ```
 
-
 ### Braces
 
 Everything besides functions and structs have the opening curly brace on the same line.
@@ -141,7 +140,6 @@ visible_child_name = gtk_stack_get_visible_child_name (GTK_STACK (self->stack));
 visible_child_name = gtk_stack_get_visible_child_name(GTK_STACK(self->stack));
 ```
 
-
 ### Header Inclusion Guards
 
 Guard header inclusion with `#pragma once` rather than the traditional
@@ -158,7 +156,6 @@ them:
 
 Only after these should you include headers.
 
-
 ### Signals
 
 Prefix signal enum names with *SIGNAL_*.
@@ -177,7 +174,6 @@ enum {
 Also note that the last element ends with a comma to reduce diff noise when
 adding further signals.
 
-
 ### Properties
 
 Prefix property enum names with *PROP_*.
@@ -215,7 +211,6 @@ In comments use full sentences with proper capitalization and punctuation.
 /* overflow check */
 ```
 
-
 ### Callbacks
 
 Signal callbacks have a *_cb* suffix.
@@ -232,7 +227,6 @@ g_signal_connect(self, "clicked", G_CALLBACK (button_clicked_cb), NULL);
 g_signal_connect(self, "clicked", G_CALLBACK (handle_button_clicked), NULL);
 ```
 
-
 ### Static Functions
 
 Static functions don't need the class prefix.  E.g. with a type foo_bar: