Make tools compiled successfully with forced C++98

Gentoo bugreport: https://bugs.gentoo.org/show_bug.cgi?id=503468

diff --git a/tools/regression/src/compiler_status.cpp b/tools/regression/src/compiler_status.cpp
index 63f8134..3f3374a 100644
--- a/tools/regression/src/compiler_status.cpp
+++ b/tools/regression/src/compiler_status.cpp
@@ -128,7 +128,7 @@ namespace
         string ln(line);
         if (ln.find("Revision: ") != string::npos)
         {
-          for(auto itr = ln.begin()+10; itr != ln.end() && isdigit(*itr); ++itr)
+          for(string::iterator itr = ln.begin()+10; itr != ln.end() && isdigit(*itr); ++itr)
             rev += *itr;
         }
       }