Problem in Makefile.am ?

[Ymil]

After executing ./autogen whit automake (1:1.14.1-4) in debian jessi, report

 Regenerating autotools files ...
src/Makefile.am:1: warning: 'CXXFLAGS' is a user variable, you should not override it;
src/Makefile.am:1: use 'AM_CXXFLAGS' instead

In line 0 the filename src/Makefile.am change the name vars, and change help the file autogen.sh.

echo " cd build; ../configure; make; su; make install"

To

echo " cd build; sudo ../configure; sudo make; sudo make install"

After executing su in the shell, a new console opens and dont execute the make install sentence.