compiletest: `run-rustfix` and `revisions` have broken interactions

[jieyouxu]

compiletest currently accepts both run-rustfix and revision directives:

• //@ run-rustfix, and
• //@ revisions: r1 ... rn

However, run-rustfix does not correctly account for revisions, because revisions + run-rustfix together tries to create a new crate named after each revision <test-name>.<revisions>, which is not a valid Rust crate name because of the ..

Example UI test where the author had to workaround it by explicitly setting #![crate_name]:

rust/tests/ui/object-safety/bare-trait-dont-suggest-dyn.new.fixed

Line 5 in 4e431fa

// FIXME: the test suite tries to create a crate called `bare_trait_dont_suggest_dyn.new`