librustc/libstd: No longer pass crate_map to start.
libstd/librustc: Make the crate_map a weak symbol that libstd links against.
tests: Remove crate_map from start.
Fix unresolved symbol error for the crate_map in libstd on os x.
Find the cratemap at runtime on windows.
auto merge of #9301 : luqmana/rust/ncm, r=brson

Get rid of the crate_map arg!

r? @brson