Add const qualifier for parameter ImFontConfig of ImFont::AddGlyph (#3461)

imgui.h

@@ -2442,7 +2442,7 @@ struct ImFont
     IMGUI_API void              BuildLookupTable();
     IMGUI_API void              ClearOutputData();
     IMGUI_API void              GrowIndex(int new_size);
-    IMGUI_API void              AddGlyph(ImFontConfig* src_cfg, ImWchar c, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x);
+    IMGUI_API void              AddGlyph(const ImFontConfig* src_cfg, ImWchar c, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x);
     IMGUI_API void              AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst = true); // Makes 'dst' character/glyph points to 'src' character/glyph. Currently needs to be called AFTER fonts have been built.
     IMGUI_API void              SetGlyphVisible(ImWchar c, bool visible);
     IMGUI_API void              SetFallbackChar(ImWchar c);

imgui_draw.cpp

@@ -2886,7 +2886,7 @@ void ImFont::GrowIndex(int new_size)
 // x0/y0/x1/y1 are offset from the character upper-left layout position, in pixels. Therefore x0/y0 are often fairly close to zero.
 // Not to be mistaken with texture coordinates, which are held by u0/v0/u1/v1 in normalized format (0.0..1.0 on each texture axis).
 // 'cfg' is not necessarily == 'this->ConfigData' because multiple source fonts+configs can be used to build one target font.
-void ImFont::AddGlyph(ImFontConfig* cfg, ImWchar codepoint, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x)
+void ImFont::AddGlyph(const ImFontConfig* cfg, ImWchar codepoint, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x)
 {
     if (cfg != NULL)
     {