Add .editorconfig

Inspired from the .editorconfig file of Mesa to ensure that we are using a consistent
code formating here while minimizing the need to customize the code editor when
working on virglrenderer.

Signed-off-by: Corentin Noël <corentin.noel@collabora.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>

.editorconfig

@@ -0,0 +1,31 @@
+# To use this config on you editor, follow the instructions at:
+# http://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+insert_final_newline = true
+tab_width = 3
+
+[*.{c,h,cpp,hpp,cc,hh}]
+indent_style = space
+indent_size = 3
+max_line_length = 90
+
+[{*.py,SCons*}]
+indent_style = space
+indent_size = 4
+
+[*.yml]
+indent_style = space
+indent_size = 2
+
+[*.rst]
+indent_style = space
+indent_size = 3
+
+[{meson.build,meson_options.txt}]
+indent_style = space
+indent_size = 3
+