BaseTools: support the NOOPT target with the GCC tool chains

BaseTools: support the NOOPT target with the GCC tool chains

Update the tools_def.template to add NOOPT support with GCC tool chains.
Also disable -flto and -Os in NOOPT target for GCC5.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Bruce Cran <bruce.cran@sandisk.com>