patch 8.0.1032: "make tags" doesn't work well on MS-Windows

Problem:    "make tags" doesn't work well on MS-Windows.
Solution:   Add or fix tags target. (Ken Takata)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index 52db561..de2c5df 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -76,6 +76,10 @@
 # Set to yes to enable terminal support.
 TERMINAL=no
 
+ifndef CTAGS
+# this assumes ctags is Exuberant ctags
+CTAGS = ctags -I INIT+ --fields=+S
+endif
 
 # Link against the shared version of libstdc++ by default.  Set
 # STATIC_STDCPLUS to "yes" to link against static version instead.
@@ -885,6 +889,12 @@
 GvimExt/gvimext.dll: GvimExt/gvimext.cpp GvimExt/gvimext.rc GvimExt/gvimext.h
 	$(MAKE) -C GvimExt -f Make_ming.mak CROSS=$(CROSS) CROSS_COMPILE=$(CROSS_COMPILE) CXX='$(CXX)' STATIC_STDCPLUS=$(STATIC_STDCPLUS)
 
+tags: notags
+	$(CTAGS) *.c *.cpp *.h if_perl.xs
+
+notags:
+	-$(DEL) tags
+
 clean:
 	-$(DEL) $(OUTDIR)$(DIRSLASH)*.o
 	-$(DEL) $(OUTDIR)$(DIRSLASH)*.res