[clangd] Silence warning when compiling with MSVC targetting x86

This fixes:
```
[5240/6995] Building CXX object tools\clang\tools\extra\clangd\CMakeFiles\obj.clangDaemon.dir\InlayHints.cpp.obj
C:\git\llvm-project\clang-tools-extra\clangd\InlayHints.cpp(1098): warning C4018: '<': signed/unsigned mismatch
```

clang-tools-extra/clangd/InlayHints.cpp

@@ -1095,7 +1095,7 @@ class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
       if (auto *Def = Callee->getDefinition()) {
         auto I = std::distance(Callee->param_begin(),
                                llvm::find(Callee->parameters(), P));
-        if (I < Callee->getNumParams()) {
+        if (I < (int)Callee->getNumParams()) {
           return Def->getParamDecl(I);
         }
       }