Update libcoro to 6.06. Fix a bug with error propagation in Lua.

Fix a bug when Tarantool exceptions were intercepted
by Lua in lua_pcall(), and converted to Lua errors.
Let Tarantool exceptions pass freely through Lua, by using
lua_call() instead of lua_pcall().

In case of any Lua error lua_call() aborts execution of the
entire process. Register lua_atpanic that converts
lua errors to Tarantool exception ER_PROC_LUA.

Unwinding the stack in this manner didn't work properly
with libcoro 6.0, which we were using. Update
libcoro library to version 6.06 to fix this problem.