lang/gcc{12,13}: Switch back to standard bootstrap

Switch back to STANDARD_BOOTSTRAP on i386, amd64 and aarch64 as default
option instead of LTO_BOOTSTRAP, forwarding the changes already commited
in the devel ports (commits daf12c76,
872d61f8, and
da4cb112) and in lang/gcc11 (commit
3e0fc5e7)

Users wanting to use LTO_BOOTSTRAP can still enable the option manually.

PR:		273397
Tested by:	exp-run (antoine)