Add opt-out from merging cc_lib object files in bindgen

[hlopko]

This is a ~rollback of
#2590, as it turns out the current behavior is incomatible with
https://bazel.build/docs/user-manual#dynamic-mode (which is very hard to use in the OSS because of
bazelbuild/bazel#4135).

In short, the dynamic mode works as follows:

• Each cc_library produces object files that are used to produce
  • a static library (often not materialized but objects get passed as --start-lib/--end-lib to the linker),
  • a shared library (only containing the objects, not transitive dependencies),
  • and an interface library (produced from .so by "stripping function bodies").
• When linking binaries, by default we use the static linking.
• When linking tests, by default we use interface libraries for linking, and shared libraries for test execution.

The motivation for this is to avoid lengthy linking actions when all that has changed between previous build is the method body (therefore Bazel produces the same interface library, so we don't need to reexecute linking action).

We do not support dynamic mode in rules_rust yet.

The current bindgen behavior works by taking object from cc_lib, and merging them into the rlib output. When dynamic_mode is on, we now have a linking action that has the rlib early on the command line, and then interface libraries of dependencies of the cc_lib, and then the interface library of the cc_lib. For reasons, lld prefers statically defined symbols, it sees that the rlib defines the same symbols as cc_lib but statically, and errors out with backward reference detected, even though cc_lib is positioned correctly.

The fix for us is to not merge objects.