Properly install dynloader.h on MSVC builds

This will enable PL/Java to be cleanly compiled, as dynloader.h is a
requirement.

Report by Chapman Flack

Patch by Michael Paquier

Backpatch through 9.1

src/backend/utils/fmgr/dfmgr.c

@@ -16,11 +16,7 @@
 
 #include <sys/stat.h>
 
-#ifndef WIN32_ONLY_COMPILER
 #include "dynloader.h"
-#else
-#include "port/dynloader/win32.h"
-#endif
 #include "lib/stringinfo.h"
 #include "miscadmin.h"
 #include "storage/shmem.h"

src/tools/msvc/Install.pm

@@ -582,7 +582,7 @@ sub CopyIncludeFiles
 		'Public headers', $target . '/include/',
 		'src/include/',   'postgres_ext.h',
 		'pg_config.h',    'pg_config_ext.h',
-		'pg_config_os.h', 'pg_config_manual.h');
+		'pg_config_os.h', 'dynloader.h', 'pg_config_manual.h');
 	lcopy('src/include/libpq/libpq-fs.h', $target . '/include/libpq/')
 	  || croak 'Could not copy libpq-fs.h';
 
@@ -605,7 +605,8 @@ sub CopyIncludeFiles
 	CopyFiles(
 		'Server headers',
 		$target . '/include/server/',
-		'src/include/', 'pg_config.h', 'pg_config_ext.h', 'pg_config_os.h');
+		'src/include/', 'pg_config.h', 'pg_config_ext.h', 'pg_config_os.h',
+		'dynloader.h');
 	CopyFiles(
 		'Grammar header',
 		$target . '/include/server/parser/',

src/tools/msvc/Solution.pm

@@ -301,6 +301,14 @@ s{PG_VERSION_STR "[^"]+"}{__STRINGIFY(x) #x\n#define __STRINGIFY2(z) __STRINGIFY
 			'src/include/storage/lwlocknames.h');
 	}
 
+	if (IsNewer(
+			'src/include/dynloader.h',
+			'src/backend/port/dynloader/win32.h'))
+	{
+		copyFile('src/backend/port/dynloader/win32.h',
+			'src/include/dynloader.h');
+	}
+
 	if (IsNewer('src/include/utils/probes.h', 'src/backend/utils/probes.d'))
 	{
 		print "Generating probes.h...\n";

src/tools/msvc/clean.bat

@@ -38,6 +38,7 @@ REM Delete files created with GenerateFiles() in Solution.pm
 if exist src\include\pg_config.h del /q src\include\pg_config.h
 if exist src\include\pg_config_ext.h del /q src\include\pg_config_ext.h
 if exist src\include\pg_config_os.h del /q src\include\pg_config_os.h
+if exist src\include\dynloader.h del /q src\include\dynloader.h
 if %DIST%==1 if exist src\backend\parser\gram.h del /q src\backend\parser\gram.h
 if exist src\include\utils\errcodes.h del /q src\include\utils\errcodes.h
 if exist src\include\utils\fmgroids.h del /q src\include\utils\fmgroids.h