rust: Make dylib-std the canonical rlib form

This removes the dylib-std suffix from rlib variants which link against
libstd dynamically. This is by far the common case.

This fixes an issue where 'm <rust_library_rlib>' would fail since Make
would expect the suffix to be included (e.g. 'm libfoo.dylib-std').

Bug: 173312517
Bug: 268086496
Test: m <rust_library_rlib> # without a suffix
Change-Id: I1e5778c57468302a8d672d5eb540047d8bb79314