add missing strcasestr checks to cmake and autotools build systems,

and update config files.

include/SDL_config_android.h

@@ -85,6 +85,7 @@
 #define HAVE_STRNCMP    1
 #define HAVE_STRCASECMP 1
 #define HAVE_STRNCASECMP 1
+#define HAVE_STRCASESTR 1
 #define HAVE_VSSCANF 1
 #define HAVE_VSNPRINTF  1
 #define HAVE_ACOS   1