patch 8.1.1306: Borland support is outdated and doesn't work

Problem:    Borland support is outdated and doesn't work.
Solution:   Remove Borland support, there are other (free) compilers
            available. (Thomas Dziedzic, Ken Takata, closes #4364)
diff --git a/src/dosinst.c b/src/dosinst.c
index ca74758..b975ff8 100644
--- a/src/dosinst.c
+++ b/src/dosinst.c
@@ -10,7 +10,7 @@
 /*
  * dosinst.c: Install program for Vim on MS-DOS and MS-Windows
  *
- * Compile with Make_mvc.mak, Make_bc3.mak, Make_bc5.mak or Make_djg.mak.
+ * Compile with Make_mvc.mak, Make_cyg.mak or Make_ming.mak.
  */
 
 /*