[d3d9] Allow arbitrary backbuffer/adapter formats

It seems these aren't linked in the way the docs made out, this fixes a crash when starting some titles.

Closes #1508

src/d3d9/d3d9_adapter.cpp

@@ -90,8 +90,10 @@ namespace dxvk {
           D3D9Format AdapterFormat,
           D3D9Format BackBufferFormat,
           BOOL       bWindowed) {
-    if (!IsSupportedBackBufferFormat(
-      AdapterFormat, BackBufferFormat, bWindowed))
+    if (!IsSupportedAdapterFormat(AdapterFormat, bWindowed))
+      return D3DERR_NOTAVAILABLE;
+
+    if (!IsSupportedBackBufferFormat(BackBufferFormat, bWindowed))
       return D3DERR_NOTAVAILABLE;
 
     return D3D_OK;

src/d3d9/d3d9_monitor.cpp

@@ -35,19 +35,6 @@ namespace dxvk {
   }
 
 
-  bool IsSupportedBackBufferFormat(
-          D3D9Format AdapterFormat,
-          D3D9Format BackBufferFormat,
-          BOOL       Windowed) {
-    if (!IsSupportedAdapterFormat(AdapterFormat, Windowed))
-      return false;
-
-    return AdapterFormat == BackBufferFormat
-        || (AdapterFormat == D3D9Format::X8R8G8B8 && BackBufferFormat == D3D9Format::A8R8G8B8)
-        || (AdapterFormat == D3D9Format::X1R5G5B5 && BackBufferFormat == D3D9Format::A1R5G5B5);
-  }
-
-
   bool IsSupportedBackBufferFormat(
           D3D9Format BackBufferFormat,
           BOOL       Windowed) {

src/d3d9/d3d9_monitor.h

@@ -26,11 +26,6 @@ namespace dxvk {
           D3D9Format Format,
           BOOL       Windowed);
 
-  bool IsSupportedBackBufferFormat(
-          D3D9Format AdapterFormat,
-          D3D9Format BackBufferFormat,
-          BOOL       Windowed);
-
   bool IsSupportedBackBufferFormat(
           D3D9Format BackBufferFormat,
           BOOL       Windowed);