patch 8.1.0779: argument for message functions is inconsistent

Problem:    Argument for message functions is inconsistent.
Solution:   Make first argument to msg() "char *".
diff --git a/src/os_amiga.c b/src/os_amiga.c
index 1cd1a19..de8bf19 100644
--- a/src/os_amiga.c
+++ b/src/os_amiga.c
@@ -1230,10 +1230,10 @@
     if (x < 0)
 # endif
     {
-	MSG_PUTS(_("Cannot execute "));
+	msg_puts(_("Cannot execute "));
 	if (cmd == NULL)
 	{
-	    MSG_PUTS(_("shell "));
+	    msg_puts(_("shell "));
 	    msg_outtrans(p_sh);
 	}
 	else
@@ -1253,7 +1253,7 @@
 	    {
 		msg_putchar('\n');
 		msg_outnum((long)x);
-		MSG_PUTS(_(" returned\n"));
+		msg_puts(_(" returned\n"));
 	    }
 	    retval = x;
 	}
@@ -1320,7 +1320,7 @@
     if (x < 0)
 # endif
     {
-	MSG_PUTS(_("Cannot execute "));
+	msg_puts(_("Cannot execute "));
 	if (use_execute)
 	{
 	    if (cmd == NULL)
@@ -1330,7 +1330,7 @@
 	}
 	else
 	{
-	    MSG_PUTS(_("shell "));
+	    msg_puts(_("shell "));
 	    msg_outtrans(shellcmd);
 	}
 	msg_putchar('\n');
@@ -1355,7 +1355,7 @@
 	    {
 		msg_putchar('\n');
 		msg_outnum((long)x);
-		MSG_PUTS(_(" returned\n"));
+		msg_puts(_(" returned\n"));
 	    }
 	    retval = x;
 	}