patch 8.1.0262: not enough testing for getftype()

Problem:    Not enough testing for getftype().
Solution:   Add a test. (Dominique Pelle, closes #3300)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 31096d7..9673a1a 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -5111,7 +5111,7 @@
 # endif
 # ifdef S_ISSOCK
 	else if (S_ISSOCK(st.st_mode))
-	    t = "fifo";
+	    t = "socket";
 # endif
 	else
 	    t = "other";