libstd: Remove `fn@`, `fn~`, and `fn&` from libstd. rs=defun
libcore: Remove `fn@`, `fn~`, and `fn&` from libcore. rs=defun
test: Remove `fn@`, `fn~`, and `fn&` from the test suite. rs=defun
Test fixes
librustdoc: Remove `fn&`, `fn~`, and `fn@` from compiletest, fuzzer, rustdoc, and rt. rs=defun
librustc: Stop parsing `fn@`, `fn~`, and `fn&`