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.

How to make PDF v1.6 files comprisable in LaTeX?

 This issue may concern when you are using TeX Live distribution of dvipdfmx.

It is a common problem that PDF v1.6 files are not comprisable in LaTeX sources to produce PDF outputs using dvipdfmx. This problem occurs due to a line at the beginning of a file dvipdfmx.cfg that reads

V 5

which specify the output PDF version to be 1.5. The problem is fixed by just replacing this line by

V 6

The file dvipdfmx.cfg is placed in <distribution>/texlive/<version>/texmf-config/dvipdfmx for typical cases of TeX Live distributions.

I encountered this problem in TeXShop with ptex2pdf for Japanese writing and found the file in the directory with <distribution> = /usr/local and <version> = 2013.