tools: disable LTO for "v8_cppgc_shared" target

"PushAllRegistersAndIterateStack" is implemented in assembly and
called from "stack.cc" via 'extern "C"'. [1]

However, LTO does not work well with symbol usage from assembly. [2]

This change workarounds the issue by disabling LTO for the target.

With GCC 10 and "./configure --enable-lto", compilation succeeds
after this change.

[1] v8/v8@c10863153
[2] https://gcc.gnu.org/wiki/LinkTimeOptimizationFAQ#Symbol_usage_from_assembly_language



Refs: #35957
Refs: #38335
Signed-off-by: Jesse Chan <jc@linux.com>

PR-URL: https://github.com/nodejs/node/pull/38346
Refs: https://github.com/nodejs/node/issues/35957
Refs: https://github.com/nodejs/node/issues/38335


Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>