Update gcc on AT 11.0
Update gcc on AT 11.0

Bump to version 7.4
Bump to revision 268015

This revision includes the merge with the gcc trunk. Thanks to Peter Bergner.

Signed-off-by: Erwan Prioul <9949cc68615082c237e6af925cacbd2ea7f2e953@linux.ibm.com>

advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain,advancetoolchain/advance-toolchain