patch 8.1.1002: "gf" does not always work when URL has a port number

Problem:    "gf" does not always work when URL has a port number. (Jakob
            Schöttl)
Solution:   When a URL is recognized also accept ":". (closes #4082)
diff --git a/src/findfile.c b/src/findfile.c
index 9730b35..690cd8f 100644
--- a/src/findfile.c
+++ b/src/findfile.c
@@ -2017,10 +2017,10 @@
     len = 0;
     while (vim_isfilec(ptr[len]) || (ptr[len] == '\\' && ptr[len + 1] == ' ')
 			 || ((options & FNAME_HYP) && path_is_url(ptr + len))
-			 || (is_url && vim_strchr((char_u *)"?&=", ptr[len]) != NULL))
+			 || (is_url && vim_strchr((char_u *)":?&=", ptr[len]) != NULL))
     {
-	// After type:// we also include ?, & and = as valid characters, so that
-	// http://google.com?q=this&that=ok works.
+	// After type:// we also include :, ?, & and = as valid characters, so that
+	// http://google.com:8080?q=this&that=ok works.
 	if ((ptr[len] >= 'A' && ptr[len] <= 'Z') || (ptr[len] >= 'a' && ptr[len] <= 'z'))
 	{
 	    if (in_type && path_is_url(ptr + len + 1))