fix CMakeLists.txt vs. configure inconsistencies

- atomic subsystem is disabled by default (changed in configure)
- SDL_WAYLAND_LIBDECOR is disabled by default if SDL_WAYLAND is not set (changed in CMakeLists.txt)

CMakeLists.txt

@@ -429,7 +429,7 @@ foreach(_SUB ${SDL_X11_OPTIONS})
 endforeach()
 set_option(SDL_WAYLAND             "Use Wayland video driver" ${UNIX_SYS})
 dep_option(SDL_WAYLAND_SHARED      "Dynamically load Wayland support" ON "SDL_WAYLAND" OFF)
-dep_option(SDL_WAYLAND_LIBDECOR    "Use client-side window decorations on Wayland" ON "SDL_WAYLAND" ON)
+dep_option(SDL_WAYLAND_LIBDECOR    "Use client-side window decorations on Wayland" ON "SDL_WAYLAND" OFF)
 dep_option(SDL_WAYLAND_LIBDECOR_SHARED     "Dynamically load libdecor support" ON "SDL_WAYLAND_LIBDECOR" OFF)
 dep_option(SDL_WAYLAND_QT_TOUCH    "QtWayland server support for Wayland video driver" ON "SDL_WAYLAND" OFF)
 set_option(SDL_RPI                 "Use Raspberry Pi video driver" ${UNIX_SYS})

configure

@@ -17954,7 +17954,12 @@ SOURCES="$SOURCES $srcdir/src/locale/*.c"
 if test "${enable_atomic+set}" = set; then :
   enableval=$enable_atomic;
 else
-  enable_atomic=yes
+  case "$host" in
+        *-*-emscripten*)
+                enable_atomic=no;;
+        *)
+                enable_atomic=yes;;
+  esac
 fi
 
 if test x$enable_atomic != xyes; then

configure.ac

@@ -415,9 +415,18 @@ SOURCES="$SOURCES $srcdir/src/locale/*.c"
 
 dnl Enable/disable various subsystems of the SDL library
 
+case "$host" in
+    *-*-emscripten*)
+        default_atomic=no
+        ;;
+    *)
+        default_atomic=yes
+        ;;
+esac
+
 AC_ARG_ENABLE(atomic,
 [AS_HELP_STRING([--enable-atomic], [Enable the atomic operations subsystem [default=yes]])],
-              , enable_atomic=yes)
+              , enable_atomic=$default_atomic)
 if test x$enable_atomic != xyes; then
     AC_DEFINE(SDL_ATOMIC_DISABLED, 1, [ ])
 else