Clean up MinGW def file generation

There were some leftovers from ancient ad-hoc ways to build on
Windows, prior to the standardization on MSVC and MinGW.  We don't
need to build a lib$(NAME)ddll.def (debug build, as opposed to
lib$(NAME)dll.def) for MinGW, since nothing uses that.  We also don't
need to build the regular .def file during distprep, since the MinGW
build environment is perfectly capable of creating that normally at
build time.

Discussion: https://www.postgresql.org/message-id/flat/0f9db9f8-47b8-a48b-6ccc-15b22b412316%402ndquadrant.com

src/Makefile.shlib

@@ -49,7 +49,6 @@
 # installdirs-lib       create installation directory $(libdir)
 # uninstall-lib         remove the libraries from $(libdir)
 # clean-lib             delete the static and shared libraries from the build dir
-# maintainer-clean-lib  delete .def files built for win32
 #
 # Typically you would add `all-lib' to the `all' target so that `make all'
 # builds the libraries.  In the most simple case it would look like this:
@@ -374,6 +373,13 @@ DLL_DEFFILE = lib$(NAME)dll.def
 
 $(shlib): $(OBJS) $(DLL_DEFFILE) | $(SHLIB_PREREQS)
 	$(CC) $(CFLAGS)  -shared -static-libgcc -o $@  $(OBJS) $(DLL_DEFFILE) $(LDFLAGS) $(LDFLAGS_SL) $(SHLIB_LINK) $(LIBS) -Wl,--out-implib=$(stlib)
+
+UC_NAME = $(shell echo $(NAME) | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ')
+
+$(DLL_DEFFILE): $(SHLIB_EXPORTS)
+	echo 'LIBRARY LIB$(UC_NAME).dll' >$@
+	echo 'EXPORTS' >>$@
+	sed -e '/^#/d' -e 's/^\(.*[ 	]\)\([0-9][0-9]*\)/    \1@ \2/' $< >>$@
 endif
 
 endif # PORTNAME == cygwin
@@ -397,32 +403,6 @@ endif # PORTNAME == cygwin || PORTNAME == win32
 	echo 'Libs.private: $(sort $(filter-out -L.% -L$(top_srcdir)/%,$(filter -L%,$(LDFLAGS) $(SHLIB_LINK)))) $(filter-out $(PKG_CONFIG_REQUIRES_PRIVATE:lib%=-l%),$(filter -l%,$(SHLIB_LINK)))' >>$@
 
 
-# We need several not-quite-identical variants of .DEF files to build
-# DLLs for Windows.  These are made from the single source file
-# exports.txt.  Since we can't assume that Windows boxes will have
-# sed, the .DEF files are always built and included in distribution
-# tarballs.
-
-ifneq (,$(SHLIB_EXPORTS))
-distprep: lib$(NAME)dll.def lib$(NAME)ddll.def
-
-UC_NAME = $(shell echo $(NAME) | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ')
-
-lib$(NAME)dll.def: $(SHLIB_EXPORTS)
-	echo '; DEF file for Makefile.shlib (MinGW)' >$@
-	echo 'LIBRARY LIB$(UC_NAME).dll' >>$@
-	echo 'EXPORTS' >>$@
-	sed -e '/^#/d' -e 's/^\(.*[ 	]\)\([0-9][0-9]*\)/    \1@ \2/' $< >>$@
-
-lib$(NAME)ddll.def: $(SHLIB_EXPORTS)
-	echo '; DEF file for Makefile.shlib (MinGW)' >$@
-	echo 'LIBRARY LIB$(UC_NAME)D.dll' >>$@
-	echo 'EXPORTS' >>$@
-	sed -e '/^#/d' -e 's/^\(.*[ 	]\)\([0-9][0-9]*\)/    \1@ \2/' $< >>$@
-
-endif # SHLIB_EXPORTS
-
-
 ##
 ## INSTALL
 ##
@@ -505,8 +485,6 @@ endif # no soname
 .PHONY: clean-lib
 clean-lib:
 	rm -f $(shlib) $(shlib_bare) $(shlib_major) $(stlib) $(exports_file) lib$(NAME).pc
-
-ifneq (,$(SHLIB_EXPORTS))
-maintainer-clean-lib:
-	rm -f lib$(NAME)dll.def lib$(NAME)ddll.def
+ifneq (,$(DLL_DEFFILE))
+	rm -f $(DLL_DEFFILE)
 endif

src/interfaces/ecpg/compatlib/Makefile

@@ -54,4 +54,4 @@ uninstall: uninstall-lib
 clean distclean: clean-lib
 	rm -f $(OBJS)
 
-maintainer-clean: distclean maintainer-clean-lib
+maintainer-clean: distclean

src/interfaces/ecpg/ecpglib/Makefile

@@ -57,4 +57,4 @@ uninstall: uninstall-lib
 clean distclean: clean-lib
 	rm -f $(OBJS)
 
-maintainer-clean: distclean maintainer-clean-lib
+maintainer-clean: distclean

src/interfaces/ecpg/pgtypeslib/Makefile

@@ -44,4 +44,4 @@ uninstall: uninstall-lib
 clean distclean: clean-lib
 	rm -f $(OBJS)
 
-maintainer-clean: distclean maintainer-clean-lib
+maintainer-clean: distclean

src/interfaces/libpq/Makefile

@@ -139,6 +139,6 @@ clean distclean: clean-lib
 # Remove files we (may have) symlinked in from other places
 	rm -f encnames.c wchar.c
 
-maintainer-clean: distclean maintainer-clean-lib
+maintainer-clean: distclean
 	$(MAKE) -C test $@
 	rm -f libpq-dist.rc