merge gcc 7.4 into gcc.old part 2.

remove our riscv changes in gcc.old. they were obsolete with GCC 5
update, let alone GCC 6. new GCC 7 has native support again.

this is really about trying to avoid conflicts when we next have
gcc

remove our riscv changes in gcc.old. they were obsolete with GCC 5
update, let alone GCC 6. new GCC 7 has native support again.

this is really about trying to avoid conflicts when we next have
gcc become gcc.old.

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merge GCC 5.4 into gcc.old.

Remove gcc.old now it is no longer used.

import GCC 4.8.5 as gcc.old, in prepartion to update GCC.