build: fix miscompilation for --enable-{tiny,color,nanorc}

This should have been part of commit 096e3627 from a month ago.

src/prototypes.h

@@ -413,7 +413,7 @@ RETSIGTYPE handle_crash(int signal);
 #endif
 RETSIGTYPE do_suspend(int signal);
 RETSIGTYPE do_continue(int signal);
-#if !defined(NANO_TINY) || defined(ENABLE_SPELLER)
+#if !defined(NANO_TINY) || defined(ENABLE_SPELLER) || defined(ENABLE_COLOR)
 void block_sigwinch(bool blockit);
 #endif
 #ifndef NANO_TINY