This patch is already merged in dolphin.

It'll appear in libretro-dolphin whenever it is rebased on top of current
dolphin source.

diff --git a/docs/gc-font-tool.cpp b/docs/gc-font-tool.cpp
index f09964609a..c43496d2fa 100644
--- a/docs/gc-font-tool.cpp
+++ b/docs/gc-font-tool.cpp
@@ -76,6 +76,7 @@
 // Font data is encoded in 2 bit greyscale and in 8x8 blocks.
 
 #include <cerrno>
+#include <cstdint>
 #include <cstring>
 #include <fstream>
 #include <iostream>