tools: Add uncrustify config file

This config file seems like a good first stab at honoring the
Mutter code style. More changes might be required once this meets
real world testing.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1924>

tools/uncrustify.cfg

@@ -0,0 +1,155 @@
+# Run `uncrustify --show-config` to see documentation for these options.
+#
+# See also: https://gitlab.gnome.org/GNOME/mutter/-/blob/master/HACKING.md
+
+#################################################################################
+# CHANGES
+#
+# The first part of this file controls what automated changes Uncrustify makes.
+#################################################################################
+
+# Files are in UTF-8
+utf8_force = true
+
+# Unix style newlines
+newlines = lf
+
+# We use spaces for alignment
+indent_with_tabs = 0
+
+# We use 2 spaces for indenting
+indent_columns = 2
+
+# We indent braces 2 spaces deep
+indent_brace = 2
+indent_case_brace = 2
+
+# We align parameters in function definitions, like this:
+#
+#     int64_t meta_string_to_date (const char   *date_string,
+#                                  int          *offset_p,
+#                                  GError      **error)
+#
+align_func_params = true
+
+# A '*' in a variable definition is considered 'dangling', rather than
+# being part of the variable type. This produces the following style of
+# alignment:
+#
+#    meta_string_to_date (const gchar  *date_string,
+#                         gint         *offset_p,
+#                         GError      **error)
+#
+align_var_def_star_style = 2  # dangling
+
+# Keep extra spaces which uncrustify thinks are not needed for alignment.
+#
+# This causes uncrustify to preserve a lot more of the existing alignment
+# in Mutter's source code, for example we can keep this:
+#
+#    meta_string_to_date (const char   *date_string,
+#                         int          *offset_p,
+#                         GError      **error)
+#
+# Instead of it being changed to this:
+#
+#    meta_string_to_date (const char  *date_string,
+#                         int         *offset_p,
+#                         GError     **error)
+#
+# Because this setting is enabled, the uncrustify process is not
+# idempodent with regards to variable alignment because we still have some
+# extra alignment in the sourcecode which uncrustify did not insert, and
+# rerunning uncrustify with different settings might remove those extra spaces.
+align_keep_extra_space = true
+
+# Ensure arithmetic operators are properly spaced, e.g:
+# foo = 1 + (2 / 4);
+sp_arith = force
+sp_arith_additive = force
+
+# Ensure spaces between assignments, e.g.:
+# foo = 2;
+# foo += 2;
+sp_assign = force
+
+# Enforce spacing around = operator (and -=, etc).
+sp_after_assign = force
+sp_before_assign = force
+
+# Remove spaces between '*', e.g.:
+# char **foo;
+sp_between_ptr_star = remove
+
+# Remove space after pointer stars.
+sp_after_ptr_star = remove
+
+# But add space before pointer return types and function
+sp_after_ptr_star_func = force
+
+# Ensure there is space between '*' and '(', e.g.:
+# typedef GNode* (* ForeachFunc) (...);
+sp_ptr_star_paren = force
+
+# & for indirections must be together with the variable
+sp_after_byref = remove
+
+# Remove spacing around ++ / -- operators.
+sp_incdec = remove
+
+# Enforce newlines between arguments at function declarations/definitions,
+# enclosing ')' belongs in the last line
+nl_func_decl_args = force
+nl_func_def_args = force
+nl_func_decl_end = remove
+
+# Enforce the right spacing inside/around/after ( ) in typedefs and
+# function calls
+sp_inside_tparen = remove
+sp_func_call_paren = force
+sp_after_tparen_close = force
+
+# Also enforce the correct multiline-ness of function
+# definitions/declarations/calls
+nl_func_decl_args = force
+nl_func_def_args = force
+nl_func_decl_end = remove
+nl_func_call_end = remove
+nl_func_call_empty = remove
+
+# Add stars at the beginning of each line in multiline comments
+cmt_star_cont = true
+
+#################################################################################
+# IGNORES
+#
+# The second part of this file controls what Uncrustify ignores.
+#################################################################################
+
+# Disable auto-alignment of macros, we often manually align the \ with
+# spaces which uncrustify doesn't support.
+align_nl_cont = false
+
+# Ignore spacing in multiline comments.
+cmt_indent_multi = false
+
+# Ignore space after casts like `(int)foo`
+sp_after_cast = ignore
+
+# Ignore spaces after ; in for (; ; ;) statements.
+sp_after_semi_for = ignore
+sp_after_semi_for_empty = ignore
+
+# Ignore Space after ! (not) operator, for example:
+#
+#     if (!home) {
+#
+sp_not = ignore
+
+# Ignore space around preprocessor '##' operator. We might want a space before
+# and no space after, for example in this:
+#
+#     #define trace(message, ...) \
+#         g_debug (message, ##__VA_ARGS__)
+#
+sp_pp_concat = ignore