cad/prusaslicer: fix font loading bug

Here is a patch fixing a font loading problem reported by Ian:

diff --git a/cad/prusaslicer/Makefile b/cad/prusaslicer/Makefile
index 55f592d288c..d04b3f39f39 100644
--- a/cad/prusaslicer/Makefile
+++ b/cad/prusaslicer/Makefile
@@ -3,7 +3,7 @@ ONLY_FOR_ARCHS = ${LP64_ARCHS}
DPB_PROPERTIES = parallel

V = 2.9.4
-REVISION = 0
+REVISION = 1
PKGNAME = prusaslicer-${V}

GH_ACCOUNT = prusa3d
diff --git a/cad/prusaslicer/patches/patch-src_slic3r_Utils_FontConfigHelp_hpp b/cad/prusaslicer/patches/patch-src_slic3r_Utils_FontConfigHelp_hpp
new file mode 100644
index 00000000000..80936b715c7
--- /dev/null
+++ b/cad/prusaslicer/patches/patch-src_slic3r_Utils_FontConfigHelp_hpp
@@ -0,0 +1,12 @@
+Index: src/slic3r/Utils/FontConfigHelp.hpp
+--- src/slic3r/Utils/FontConfigHelp.hpp.orig
++++ src/slic3r/Utils/FontConfigHelp.hpp
+@@ -6,7 +6,7 @@
+ #define slic3r_FontConfigHelp_hpp_
+
+ #include <string>
+-#ifdef __linux__
++#if defined(__linux__) || defined(__OpenBSD__)
+ #define EXIST_FONT_CONFIG_INCLUDE
+