[BOLT][AArch64] Fix LDR relocation type in ADRP+LDR sequence

`R_AARCH64_ADD_ABS_LO12_NC` is for the `ADD` instruction in the `ADRP+ADD`
sequence. For `ADRP+LDR` sequence generated in LDR relaxation, relocation
type for `LDR` should be `R_AARCH64_LDST64_ABS_LO12_NC` if it is 64-bit
integer load or `R_AARCH64_LDST32_ABS_LO12_NC` if 32-bit.

Author: yozhu

bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp

@@ -640,7 +640,8 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     Insts[1].addOperand(MCOperand::createImm(0));
     Insts[1].addOperand(MCOperand::createImm(0));
     setOperandToSymbolRef(Insts[1], /* OpNum */ 2, Target, 0, Ctx,
-                          ELF::R_AARCH64_ADD_ABS_LO12_NC);
+                          isLDRXl(LDRInst) ? ELF::R_AARCH64_LDST64_ABS_LO12_NC
+                                           : ELF::R_AARCH64_LDST32_ABS_LO12_NC);
     return Insts;
   }