install-deps.sh: correct gcc version info as major.minor.patch

install-deps.sh: correct gcc version info as major.minor.patch

On ubuntu 18.04, "gcc -dumpversion" output "7", it result in
that below check will return false:
    dpkg --compare-versions 7 ge 7.0
Then, this script will install other gcc.

Actully, the full gcc version "gcc -dumpfullversion" output is
"7.3.0", than below check will turn true:
    dpkg --compare-version 7.3.0 ge 7.0
So, there's no need to install other gcc.

In case of hitting error on ubuntu16.04, use below parameter:
   gcc -dumpfullversion -dumpversion

Signed-off-by: Changcheng Liu <changcheng.liu@intel.com>