Try to fix non-MSVC Windows builds in the wake of logical replication.

pgoutput evidently needs to be built without -DBUILDING_DLL.  (It seems
like a pretty bad idea that these makefiles need to know exactly where
all the shlibs are in the tree, or maybe what's bad is putting them under
src/backend/.  But right now is not the time to redesign that.)

Also, remove "override CPPFLAGS" in pgoutput's Makefile.  I don't think
that that actually has any bad consequences, but it's certainly useless
in a directory that has no .h files, and it might be contributing to the
failure somehow.

Per buildfarm.

src/backend/replication/pgoutput/Makefile

@@ -12,8 +12,6 @@ subdir = src/backend/replication/pgoutput
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(srcdir) $(CPPFLAGS)
-
 OBJS = pgoutput.o $(WIN32RES)
 PGFILEDESC = "pgoutput - standard logical replication output plugin"
 NAME = pgoutput

src/makefiles/Makefile.cygwin

@@ -16,13 +16,15 @@ CFLAGS_SL =
 
 ifneq (,$(findstring backend,$(subdir)))
 ifeq (,$(findstring conversion_procs,$(subdir)))
-ifeq (,$(findstring snowball,$(subdir)))
 ifeq (,$(findstring libpqwalreceiver,$(subdir)))
+ifeq (,$(findstring replication/pgoutput,$(subdir)))
+ifeq (,$(findstring snowball,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL
 endif
 endif
 endif
 endif
+endif
 
 ifneq (,$(findstring src/common,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL

src/makefiles/Makefile.win32

@@ -14,13 +14,15 @@ CFLAGS_SL =
 
 ifneq (,$(findstring backend,$(subdir)))
 ifeq (,$(findstring conversion_procs,$(subdir)))
-ifeq (,$(findstring snowball,$(subdir)))
 ifeq (,$(findstring libpqwalreceiver,$(subdir)))
+ifeq (,$(findstring replication/pgoutput,$(subdir)))
+ifeq (,$(findstring snowball,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL
 endif
 endif
 endif
 endif
+endif
 
 ifneq (,$(findstring src/common,$(subdir)))
 override CPPFLAGS+= -DBUILDING_DLL