Reduce default static_input_buffer_size.

There seems to be diminishing returns after 32 bytes, and it takes
significantly less space. (It's only a default, anyway.)

heatshrink_config.h

@@ -10,7 +10,7 @@
     #define HEATSHRINK_FREE(P, SZ) free(P)
 #else
     /* Required parameters for static configuration */
-    #define HEATSHRINK_STATIC_INPUT_BUFFER_SIZE 256
+    #define HEATSHRINK_STATIC_INPUT_BUFFER_SIZE 32
     #define HEATSHRINK_STATIC_WINDOW_BITS 8
     #define HEATSHRINK_STATIC_LOOKAHEAD_BITS 4
 #endif