patch 8.2.2408: MinGW: "--preprocessor" flag no longer supported

Problem:    MinGW: "--preprocessor" flag no longer supported.
Solution:   Remove the flag, use the defaults. (Christopher Wellons,
            closes #7741)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index b6dd928..8895d27 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -220,7 +220,6 @@
 else
 WINDRES := windres
 endif
-WINDRES_CC = $(CC)
 
 # Get the default ARCH.
 ifndef ARCH
@@ -514,7 +513,8 @@
 
 CFLAGS = -I. -Iproto $(DEFINES) -pipe -march=$(ARCH) -Wall
 CXXFLAGS = -std=gnu++11
-WINDRES_FLAGS = --preprocessor="$(WINDRES_CC) -E -xc" -DRC_INVOKED
+# This used to have --preprocessor, but it's no longer supported
+WINDRES_FLAGS =
 EXTRA_LIBS =
 
 ifdef GETTEXT