[llvm] [NFC][InstrInfoEmitter] Include location of inst definition in comment (PR #156927)

[Rahul Joshi via llvm-commits]

jurahul wrote:

```
                                       old        new     % increase
AArch64GenInstrInfo.inc            2655197    3258785     22.73%
AMDGPUGenInstrInfo.inc            23086409   25991133     12.58%
ARCGenInstrInfo.inc                 249828     290249     16.18%
ARMGenInstrInfo.inc                1544602    1782064     15.37%
AVRGenInstrInfo.inc                 185376     212756     14.77%
BPFGenInstrInfo.inc                 178051     205677     15.52%
CSKYGenInstrInfo.inc                237436     286008     20.46%
DirectXGenInstrInfo.inc             117364     133948     14.13%
HexagonGenInstrInfo.inc             998187    1208303     21.05%
LanaiGenInstrInfo.inc               147120     169398     15.14%
LoongArchGenInstrInfo.inc           525739     677574     28.88%
M68kGenInstrInfo.inc                486862     566026     16.26%
MSP430GenInstrInfo.inc              218135     255037     16.92%
MipsGenInstrInfo.inc                908964    1077987     18.60%
NVPTXGenInstrInfo.inc              1880227    2185637     16.24%
PPCGenInstrInfo.inc                 818220     992338     21.28%
R600GenInstrInfo.inc                228852     264643     15.64%
RISCVGenInstrInfo.inc              5542500    6326909     14.15%
SPIRVGenInstrInfo.inc               275777     315732     14.49%
SparcGenInstrInfo.inc               242143     291428     20.35%
SystemZGenInstrInfo.inc             897855    1099037     22.41%
VEGenInstrInfo.inc                 2403221    2945974     22.58%
WebAssemblyGenInstrInfo.inc         788063     911669     15.68%
X86GenInstrInfo.inc                8169180    9305799     13.91%
XCoreGenInstrInfo.inc               186533     215773     15.68%
XtensaGenInstrInfo.inc              214711     248995     15.97%
```

So average is a 20% increase in the size.

https://github.com/llvm/llvm-project/pull/156927