Update clang-format to version 11

This is taken from the Godot repository, so formatting is similar. This
updates the style rules as well.

Also fix style in files to conform with this version.

.github/workflows/ci.yml

@@ -147,14 +147,22 @@ jobs:
 
   static-checks:
     name: Static Checks (clang-format)
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
-    
+        uses: actions/checkout@v2
+
+      - name: Make apt sources.list use the default Ubuntu repositories
+        run: |
+          sudo rm -f /etc/apt/sources.list.d/*
+          sudo cp -f misc/ci/sources.list /etc/apt/sources.list
+          sudo apt-get update
+
       - name: Install dependencies
         run: |
-          sudo apt-get install clang-format-8
+          sudo apt-get install -qq dos2unix recode clang-format-11
+          sudo update-alternatives --remove-all clang-format
+          sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-11 100
 
       - name: Style checks via clang-format
         run: |