hardcode executable path

Index: external/libutil/libs/common/src/getExecutablePath.cpp
--- external/libutil/libs/common/src/getExecutablePath.cpp.orig
+++ external/libutil/libs/common/src/getExecutablePath.cpp
@@ -83,6 +83,9 @@ std::string getExecutablePath()
 
 std::string getExecutablePath()
 {
+#ifdef __OpenBSD__
+    return "${LOCALBASE}/bin/s25client";
+#else
     std::array<int, 4> mib = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
     std::vector<char> buf(1024, 0);
     size_t size = buf.size();
@@ -95,6 +98,7 @@ std::string getExecutablePath()
     using bfs::canonical;
     bfs::path p(canonical(path, ec));
     return ec ? "" : p.make_preferred().string();
+#endif
 }
 
 #elif(BOOST_OS_LINUX)
