This eliminates the need for archs_enable() and eliminates the racey
initialization.
This makes the architecture-specific init, option, and destroy functions
non-static so that they may be called from a different file.
* Remove `big_endian` field of `cs_struct`
Added a helper macro `MODE_IS_BIG_ENDIAN()` to check if
`CS_MODE_BIG_ENDIAN` is set.
Refactored `cs_open()` check for valid mode out of arch-specific code
into arch-independent code. Also added a valid mode check to
`cs_option()`. The checks use a new global array
`arch_disallowed_mode_mask[]`, which is initialized in the arch-specific
`*_enable()` functions.
Fixes bug where endianness could not be set for ppc.
* Fix Mac OS brew for Travis CI
Nguyen Anh Quynh