* mips.h: Add macros for cop0, cop1 cop2 and cop3.

	* mips.h: Add macros for cop0, cop1 cop2 and cop3.
	Change mips_opcodes from const array to a pointer,
	and change bfd_mips_num_opcodes from const int to int,
	so that we can increase the size of the mips opcodes table
	dynamically.