Remove superfluous -DFRONTEND.

The majority practice is to add -DFRONTEND in directories building files
that are, at other times, built for the backend.  Some directories
lacking that property added a noise -DFRONTEND in one build system.
Remove the excess flags, for consistency.

src/bin/pg_upgrade/Makefile

@@ -11,7 +11,7 @@ OBJS = check.o controldata.o dump.o exec.o file.o function.o info.o \
        option.o page.o parallel.o pg_upgrade.o relfilenode.o server.o \
        tablespace.o util.o version.o $(WIN32RES)
 
-override CPPFLAGS := -DFRONTEND -DDLSUFFIX=\"$(DLSUFFIX)\" -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
+override CPPFLAGS := -DDLSUFFIX=\"$(DLSUFFIX)\" -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
 
 
 all: pg_upgrade

src/tools/msvc/Mkvcbuild.pm

@@ -379,7 +379,6 @@ sub mkvcbuild
 	$pgregress_ecpg->AddIncludeDir('src\port');
 	$pgregress_ecpg->AddIncludeDir('src\test\regress');
 	$pgregress_ecpg->AddDefine('HOST_TUPLE="i686-pc-win32vc"');
-	$pgregress_ecpg->AddDefine('FRONTEND');
 	$pgregress_ecpg->AddLibrary('ws2_32.lib');
 	$pgregress_ecpg->AddDirResourceFile('src\interfaces\ecpg\test');
 	$pgregress_ecpg->AddReference($libpgcommon, $libpgport);
@@ -395,7 +394,6 @@ sub mkvcbuild
 	$isolation_tester->AddIncludeDir('src\test\regress');
 	$isolation_tester->AddIncludeDir('src\interfaces\libpq');
 	$isolation_tester->AddDefine('HOST_TUPLE="i686-pc-win32vc"');
-	$isolation_tester->AddDefine('FRONTEND');
 	$isolation_tester->AddLibrary('ws2_32.lib');
 	$isolation_tester->AddDirResourceFile('src\test\isolation');
 	$isolation_tester->AddReference($libpq, $libpgcommon, $libpgport);
@@ -407,7 +405,6 @@ sub mkvcbuild
 	$pgregress_isolation->AddIncludeDir('src\port');
 	$pgregress_isolation->AddIncludeDir('src\test\regress');
 	$pgregress_isolation->AddDefine('HOST_TUPLE="i686-pc-win32vc"');
-	$pgregress_isolation->AddDefine('FRONTEND');
 	$pgregress_isolation->AddLibrary('ws2_32.lib');
 	$pgregress_isolation->AddDirResourceFile('src\test\isolation');
 	$pgregress_isolation->AddReference($libpgcommon, $libpgport);
@@ -640,7 +637,6 @@ sub mkvcbuild
 	$pgregress->AddFile('src\test\regress\pg_regress_main.c');
 	$pgregress->AddIncludeDir('src\port');
 	$pgregress->AddDefine('HOST_TUPLE="i686-pc-win32vc"');
-	$pgregress->AddDefine('FRONTEND');
 	$pgregress->AddLibrary('ws2_32.lib');
 	$pgregress->AddDirResourceFile('src\test\regress');
 	$pgregress->AddReference($libpgcommon, $libpgport);