dwrite_2.idl: Protect from D3DCOLORVALUE redefinition.
diff --git a/include/dwrite_2.idl b/include/dwrite_2.idl
index 26523da..d2960eb 100644
--- a/include/dwrite_2.idl
+++ b/include/dwrite_2.idl
@@ -47,6 +47,7 @@
     FLOAT heightIncludingTrailingWhitespace;
 } DWRITE_TEXT_METRICS1;
 
+cpp_quote("#ifndef D3DCOLORVALUE_DEFINED")
 typedef struct _D3DCOLORVALUE
 {
     union {
@@ -66,6 +67,8 @@
         FLOAT dvA;
     };
 } D3DCOLORVALUE;
+cpp_quote("#define D3DCOLORVALUE_DEFINED")
+cpp_quote("#endif")
 
 typedef D3DCOLORVALUE DWRITE_COLOR_F;