BaseTools/tools_def.template: remove GCC46 leaf definitions

BaseTools/tools_def.template: remove GCC46 leaf definitions

Remove the "leaf" definitions for GCC46. These definitions are never
referenced in "tools_def.template" (they are the last GCC46 mentions in
the file), so their removal can't break other definitions. Instead, their
erasure turns other definitions into leaves (subject to further removal).

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1377
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>