don't warn about Sprite having the wrong number of states

stepmania/src/Sprite.cpp

@@ -691,6 +691,9 @@ void Sprite::SetState( int iNewState )
 	// is loaded in place of a multi-frame sprite.  We want to know about these
 	// problems in debug builds, but they're not fatal.
 	if( iNewState < 0  ||  iNewState >= (int)m_States.size() )
+	{
+		// Don't warn about number of states in "_blank".
+		if( m_pTexture->GetID().filename.Find("_blank") == -1 )
 		{
 			CString sError;
 			if( m_pTexture )
@@ -701,6 +704,7 @@ void Sprite::SetState( int iNewState )
 					this->m_sName.c_str(), iNewState );
 			Dialog::OK( sError );
 		}
+	}
 
 	CLAMP(iNewState, 0, (int)m_States.size()-1);
 	m_iCurState = iNewState;