Mark alternative ImColor constructors as constexpr (#6656)

imgui.h

@@ -2468,8 +2468,8 @@ struct ImColor
     constexpr ImColor()                                             { }
     constexpr ImColor(float r, float g, float b, float a = 1.0f)    : Value(r, g, b, a) { }
     constexpr ImColor(const ImVec4& col)                            : Value(col) {}
-    ImColor(int r, int g, int b, int a = 255)                       { float sc = 1.0f / 255.0f; Value.x = (float)r * sc; Value.y = (float)g * sc; Value.z = (float)b * sc; Value.w = (float)a * sc; }
-    ImColor(ImU32 rgba)                                             { float sc = 1.0f / 255.0f; Value.x = (float)((rgba >> IM_COL32_R_SHIFT) & 0xFF) * sc; Value.y = (float)((rgba >> IM_COL32_G_SHIFT) & 0xFF) * sc; Value.z = (float)((rgba >> IM_COL32_B_SHIFT) & 0xFF) * sc; Value.w = (float)((rgba >> IM_COL32_A_SHIFT) & 0xFF) * sc; }
+    constexpr ImColor(int r, int g, int b, int a = 255)             { float sc = 1.0f / 255.0f; Value.x = (float)r * sc; Value.y = (float)g * sc; Value.z = (float)b * sc; Value.w = (float)a * sc; }
+    constexpr ImColor(ImU32 rgba)                                   { float sc = 1.0f / 255.0f; Value.x = (float)((rgba >> IM_COL32_R_SHIFT) & 0xFF) * sc; Value.y = (float)((rgba >> IM_COL32_G_SHIFT) & 0xFF) * sc; Value.z = (float)((rgba >> IM_COL32_B_SHIFT) & 0xFF) * sc; Value.w = (float)((rgba >> IM_COL32_A_SHIFT) & 0xFF) * sc; }
     inline operator ImU32() const                                   { return ImGui::ColorConvertFloat4ToU32(Value); }
     inline operator ImVec4() const                                  { return Value; }