sdl: fix SDL_AUTORECONF typo in comment

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/sdl/sdl.mk

@@ -12,7 +12,7 @@ SDL_LICENSE_FILES = COPYING
 SDL_INSTALL_STAGING = YES
 
 # we're patching configure.in, but package cannot autoreconf with our version of
-# autotools, so we have to do it manually instead of setting SD_AUTORECONF = YES
+# autotools, so we have to do it manually instead of setting SDL_AUTORECONF = YES
 define SDL_RUN_AUTOGEN
 	cd $(@D) && PATH=$(HOST_PATH) ./autogen.sh
 endef