patch 9.1.0527: inconsistent parameter in Makefiles for Vim executable

Problem:  inconsistent parameter in Makefiles for Vim executable
Solution: consistently use $VIMPROG across all Makefiles
          (RestorerZ)

closes: #15099

Signed-off-by: RestorerZ <restorer@mail2k.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/Makefile b/Makefile
index f4db80f..ad07376 100644
--- a/Makefile
+++ b/Makefile
@@ -56,7 +56,7 @@
 indenttest:
 	cd runtime/indent && \
 		$(MAKE) clean && \
-		$(MAKE) test VIM="$(VIM_FOR_INDENTTEST)"
+		$(MAKE) test VIMPROG="$(VIM_FOR_INDENTTEST)"
 
 # Executable used for running the syntax tests.
 VIM_FOR_SYNTAXTEST = ../../src/vim
@@ -249,9 +249,6 @@
 VDOT	= $(MAJOR).$(MINOR)
 VIMRTDIR = vim$(VERSION)
 
-# Vim used for conversion from "unix" to "dos"
-VIM	= vim
-
 # How to include Filelist depends on the version of "make" you have.
 # If the current choice doesn't work, try the other one.