.editorconfig: remove autotools files + trim whitespace from cmake files

.editorconfig

@@ -19,34 +19,20 @@ indent_style = space
 [{CMakeLists.txt,cmake/*.cmake}]
 indent_size = 2
 indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
 
-[{cmake_uninstall.cmake.in,test/CMakeLists.txt}]
-indent_size = 4
-indent_style = space
-
-[configure.ac]
-# Inconsistently 2-, 4- or occasionally 3-space indented, but mostly 4,
-# so let's use 4 for new code
+[{cmake_uninstall.cmake.in,test/CMakeLists.txt,./SDL3Config.cmake.in}]
 indent_size = 4
 indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
 
 [{Makefile.*,*.mk,*.sln,*.pbxproj,*.plist}]
 indent_size = 8
 indent_style = tab
 tab_width = 8
 
-[Makefile.os2]
-indent_size = 4
-indent_style = space
-
-[test/Makefile.os2]
-indent_size = 2
-indent_style = space
-
-[{src/core/os2/geniconv/makefile,src/core/os2/geniconv/os2cp.c}]
-indent_size = 2
-indent_style = space
-
 [src/joystick/controller_type.*]
 indent_style = tab