imgui_single_file: include imgui_freetype.cpp if the define is set.

.h not often needed but doesn't cost much to include.

misc/single_file/imgui_single_file.h

@@ -8,6 +8,9 @@
 // Before you include this file in *one* C++ file to create the implementation.
 // Using this in your project will leak the contents of imgui_internal.h and ImVec2 operators in this compilation unit.
 #include "../../imgui.h"
+#ifdef IMGUI_ENABLE_FREETYPE
+#include "../../misc/freetype/imgui_freetype.h"
+#endif
 
 #ifdef IMGUI_IMPLEMENTATION
 #include "../../imgui.cpp"
@@ -15,4 +18,7 @@
 #include "../../imgui_draw.cpp"
 #include "../../imgui_tables.cpp"
 #include "../../imgui_widgets.cpp"
+#ifdef IMGUI_ENABLE_FREETYPE
+#include "../../misc/freetype/imgui_freetype.cpp"
+#endif
 #endif