getProcessPath() doesn't work on OpenBSD.

Index: src/version.cpp
--- src/version.cpp.orig
+++ src/version.cpp
@@ -424,7 +424,7 @@ void Exiv2::dumpLibraryInfo(std::ostream& os, const st
   output(os, keys, "version", __VERSION__);
   output(os, keys, "date", __DATE__);
   output(os, keys, "time", __TIME__);
-  output(os, keys, "processpath", Exiv2::getProcessPath());
+  //output(os, keys, "processpath", Exiv2::getProcessPath());
 #ifdef EXV_ENABLE_NLS
   output(os, keys, "localedir", EXV_LOCALEDIR);
 #endif