This flag should mangle as such:

ld: error: undefined symbol: v8::platform::NewDefaultPlatform(int,
v8::platform::IdleTaskSupport, v8::platform::InProcessStackDumping,
std::unique_ptr<v8::TracingController,
std::default_delete<v8::TracingController> >)

Instead of: (note the std::__Cr:: instead of std::)

000000000000f5e0 T v8::platform::NewDefaultPlatform(int,
v8::platform::IdleTaskSupport, v8::platform::InProcessStackDumping,
std::__Cr::unique_ptr<v8::TracingController,
std::__Cr::default_delete<v8::TracingController> >)

use the monolith build thing that's part of v8. In theory that should
do the right thing already.

Flag v8_use_snapshot = false added now.

The previous guess I made didn't make sense and was unrelated.

Should be related to the following runtime issue:

 #
 # Fatal error in , line 0
 # Failed to deserialize the V8 snapshot blob. This can mean that the
 snapshot blob file is corrupted or missing.
 #
 #
 #
 #FailureMessage Object: 0x7f40ed7b8230

This will also require a bunch of fixes in Starcry.