gdb: LoongArch: Add instruction definition for process record

gdb: LoongArch: Add instruction definition for process record

GDB provides a special process record function that can record a log
of the process execution. The core of this feature is need to record
the execution of all instructions. This patch adds opcode definitions
and judgments in gdb/arch/loongarch-insn.h. This is preparation for
later patch on LoongArch, there is no effect for the other archs with
this patch.

The LoongArch opcode and mask definitions are obtained from
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=opcodes/loongarch-opc.c
LoongArch instruction description refer to the LoongArch Reference Manual:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html

Signed-off-by: Hui Li <lihui@loongson.cn>
Reviewed-By: Guinevere Larsen <guinevere@redhat.com>
Approved-By: Tom Tromey <tom@tromey.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>