lang/gcc11: 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 daf12c76bd531335f58e7602afd3bc8da8fc5c33,
872d61f8ead10a6d935117876cf60057a46770ff, and
da4cb11216a7ed594d5dc453deb4693b48c3c7e9).

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

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