GDB installation

You can download the latest and compile it by yourself

wget http://ftp.gnu.org/gnu/gdb/gdb-7.5.tar.gz
tar xvfz gdb-7.5.tar.gz
cd gdb-7.5
./configure
make
cp gdb/gdb /usr/local/bin

Take care about that the /usr/local/bin is at the beginning of the PATH you are using while running QtCreator
You can place the following line into your .profile

export PATH=$PATH:/usr/local/bin