llvm-nm error if Cargo.toml uses [[bin]]

[alastairreid]

If Cargo.toml has

name = "foo" ... [[bin]] name = "bar" path = "src/main.rs"

then we check for "main" in target/$tgt/debug/deps/foo.bc but we should be checking for it in target/$tgt/debug/deps/bar.bc.

Since we are checking the wrong file, we get an error like

(Discovered in coreutils)

[alastairreid]

Fixed