patch 9.1.0623: Mingw: errors when trying to delete non-existing files

Problem:  Mingw: warnings when trying to delete non-existing files
Solution: Use "rm -f" instead of "rm" to suppress errors for
          non-existing files (Ken Takata)

closes: #15350

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/GvimExt/Make_ming.mak b/src/GvimExt/Make_ming.mak
index 85017d8..06ec7b6 100644
--- a/src/GvimExt/Make_ming.mak
+++ b/src/GvimExt/Make_ming.mak
@@ -29,7 +29,7 @@
 endif
 
 ifeq ($(CROSS),yes)
-DEL = rm
+DEL = rm -f
 ifeq ($(MINGWOLD),yes)
 CXXFLAGS := -O2 -fvtable-thunks
 else
@@ -38,7 +38,7 @@
 else
 CXXFLAGS := -O2
 ifneq (sh.exe, $(SHELL))
-DEL = rm
+DEL = rm -f
 else
 DEL = del
 endif