check presence of d3dx9effect.h

It's part of mingw-w64, but was removed from the Windows SDK a long time ago.

config.h.meson

@@ -104,6 +104,9 @@
 /* Define if the compiler supports typeof. */
 #mesondefine HAVE_CXX_TYPEOF
 
+/* Define to 1 if you have the <d3dx9effect.h> header file. */
+#mesondefine HAVE_D3DX9EFFECT_H
+
 /* Define to 1 if you have the `dirfd' function. */
 #mesondefine HAVE_DIRFD
 

configure.ac

@@ -2792,6 +2792,7 @@ dnl
 dnl DXGI debug
 dnl
 AC_CHECK_HEADERS([dxgidebug.h])
+AC_CHECK_HEADERS([d3dx9effect.h])
 
 dnl
 dnl IStorageFolder

meson.build

@@ -270,6 +270,7 @@ check_c_headers = [
     ['zlib.h', { 'args' : [contrib_inc_args] }],
     ['wordexp.h'],
     ['dxgidebug.h'],
+    ['d3dx9effect.h'],
     ['GL/wglew.h',
         { 'prefix' : ['#include <windows.h>', '#include <GL/glew.h>'],
           'args' : [contrib_inc_args] }],