LoongArch: Add tls transition support.

Transitions between DESC->IE/LE and IE->LE are supported now.
1. For DESC -> LE:
   pcalau12i  $a0,%desc_pc_hi20(var)     =>  lu12i.w $a0,%le_hi20(var)
   addi.d     $a0,$a0,%desc_pc_lo12(var) =>  ori $a0,$a0,%le_lo12(var)
   ld.d       $a1,$a0,%desc_ld(var)      =>  NOP
   jirl       $ra,$a1,%desc_call(var)	 =>  NOP
   add.d      $a0,$a0,$tp
2. For DESC -> IE:
   pcalau12i  $a0,%desc_pc_hi20(var)     =>  pcalau12i $a0,%ie_pc_hi20(var)
   addi.d     $a0,$a0,%desc_pc_lo12(var) =>  ld.d $a0,$a0,%ie_pc_lo12(var)
   ld.d       $a1,$a0,%desc_ld(var)      =>  NOP
   jirl       $ra,$a1,%desc_call(var)	 =>  NOP
   add.d      $a0,$a0,$tp
3. For IE -> LE:
   pcalau12i  $a0,%ie_pc_hi20(var)       =>  lu12i.w $a0,%le_hi20(var)
   ld.d       $a0,$a0,%ie_pc_lo12(var)   =>  ori $a0,$a0,%le_lo12(var)
   add.d      $a0,$a0,$tp
4. When a tls variable is accessed using both DESC and IE, DESC transitions
   to IE and uses the same GOT entry as IE.

include/opcode/loongarch.h

@@ -42,6 +42,12 @@ extern "C"
     ((value) < (-(1 << ((bits) - 1) << align)) 	\
       || (value) > ((((1 << ((bits) - 1)) - 1) << align)))
 
+  #define LARCH_LU12I_W 0x14000000
+  #define LARCH_ORI 0x03800000
+  #define LARCH_LD_D 0x28c00000
+  #define LARCH_RD_A0 0x04
+  #define LARCH_RD_RJ_A0 0x084
+
   typedef uint32_t insn_t;
 
   struct loongarch_opcode