Precise globals require a whole program optimization pass that is hard
to support when building packages separately. This patch removes support
for these globals by converting the last use (Linux) to use
linker-defined symbols instead.
For details, see: https://github.com/tinygo-org/tinygo/issues/2870
This allows for adding more advanced tests, for example tests that use
the compiler package so that test sources can be written in Go instead
of LLVM IR.