Remove: officially mark Vista as no longer supported (#11531)

It is very likely Vista hasn't been working for years, but the
amount of users that use an OS that has been EoL for over 11 years
is very small, so reports happen rarely.

(cherry picked from commit b866e52b17)

docs/directory_structure.md

@@ -19,14 +19,14 @@ your operating system:
     - Windows:
         - `C:\My Documents\OpenTTD` (95, 98, ME)
         - `C:\Documents and Settings\<username>\My Documents\OpenTTD` (2000, XP)
-        - `C:\Users\<username>\Documents\OpenTTD` (Vista, 7, 8.1, 10, 11)
+        - `C:\Users\<username>\Documents\OpenTTD` (7, 8.1, 10, 11)
     - macOS: `~/Documents/OpenTTD`
     - Linux: `$XDG_DATA_HOME/openttd` which is usually `~/.local/share/openttd`
        when built with XDG base directory support, otherwise `~/.openttd`
 3. The shared directory
     - Windows:
         - `C:\Documents and Settings\All Users\Shared Documents\OpenTTD` (2000, XP)
-        - `C:\Users\Public\Documents\OpenTTD` (Vista, 7, 8.1, 10, 11)
+        - `C:\Users\Public\Documents\OpenTTD` (7, 8.1, 10, 11)
     - macOS: `/Library/Application Support/OpenTTD`
     - Linux: not available
 4. The binary directory (where the OpenTTD executable is)

os/windows/openttd.manifest

@@ -15,8 +15,6 @@
   </application>
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
-      <!--This Id value indicates the application supports Windows Vista functionality -->
-      <supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}"/>
       <!--This Id value indicates the application supports Windows 7 functionality-->
       <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
       <!--This Id value indicates the application supports Windows 8 functionality-->

src/sound/win32_s.cpp

@@ -70,7 +70,7 @@ const char *SoundDriver_Win32::Start(const StringList &parm)
 	wfex.nAvgBytesPerSec = wfex.nSamplesPerSec * wfex.nBlockAlign;
 
 	/* Limit buffer size to prevent overflows. */
-	_bufsize = GetDriverParamInt(parm, "bufsize", IsWindowsVistaOrGreater() ? 8192 : 4096);
+	_bufsize = GetDriverParamInt(parm, "bufsize", 8192);
 	_bufsize = std::min<int>(_bufsize, UINT16_MAX);
 
 	try {

src/video/win32_v.cpp

@@ -1266,7 +1266,7 @@ static const char *SelectPixelFormat(HDC dc)
 		0, 0, 0, 0                     // Ignored/reserved.
 	};
 
-	if (IsWindowsVistaOrGreater()) pfd.dwFlags |= PFD_SUPPORT_COMPOSITION; // Make OpenTTD compatible with Aero.
+	pfd.dwFlags |= PFD_SUPPORT_COMPOSITION; // Make OpenTTD compatible with Aero.
 
 	/* Choose a suitable pixel format. */
 	int format = ChoosePixelFormat(dc, &pfd);