patch 8.1.1621: Amiga: time.h included twice

Problem:    Amiga: time.h included twice.
Solution:   Remove include from evalfunc.c, move outside of #ifdef in
            os_amiga.h. (Ola Söder, closes #4607)

src/os_amiga.h

@@ -90,10 +90,11 @@ typedef long off_t;
 # include <unistd.h>
 # include <limits.h>
 # include <errno.h>
-# include <time.h>
 # include <dirent.h>
 #endif
 
+#include <time.h>	// for strftime() and others
+
 #ifndef PROTO
 /*
  * arpbase.h must be included before functions.h