gcc and gfortran on OS X 10.9 Marvericks

A new release of OS X 10.9 Marvericks was installed on my MacBook 15-inch Retina Pro 2012.
I kept all softwares previously installed on OS X 10.8 as they were. All of them are working
well without a change except for the following.

gcc 4.8.1
========
I needed to install the Command Line Tools by issuing 
%xcode-select --install
to make gcc work. This is necessary regardless whether one has
already installed Xquartz or not.

gfortran
=========
I need
-fno-underscoring
option at the load time to use gnu extensions. 
This was not required before in my case.