gcc-8.inc: Update to work with Poky gcc 8.3
gcc-8.inc: Update to work with Poky gcc 8.3

Poky has updated gcc and changed a lot of number prefixes in patches name,
as well as renamed gcc-8.*.inc and local-file-folder.
Update gcc-8.inc to work with these new changes.

Signed-off-by: Trung Do <64081e6b7eb2b24289b8a4e51cef9836ddf28af2@toshiba-tsdv.com>

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