[lldb][NFC] Replace some counting loops with std::distance

Author: Endilll

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -5361,11 +5361,8 @@ uint32_t TypeSystemClang::GetNumChildren(lldb::opaque_compiler_type_t type,
           num_children += cxx_record_decl->getNumBases();
         }
       }
-      clang::RecordDecl::field_iterator field, field_end;
-      for (field = record_decl->field_begin(),
-          field_end = record_decl->field_end();
-           field != field_end; ++field)
-        ++num_children;
+      num_children += std::distance(record_decl->field_begin(),
+                               record_decl->field_end());
     }
     break;
 
@@ -5576,13 +5573,8 @@ uint32_t TypeSystemClang::GetNumFields(lldb::opaque_compiler_type_t type) {
       if (record_type) {
         clang::RecordDecl *record_decl = record_type->getDecl();
         if (record_decl) {
-          uint32_t field_idx = 0;
-          clang::RecordDecl::field_iterator field, field_end;
-          for (field = record_decl->field_begin(),
-              field_end = record_decl->field_end();
-               field != field_end; ++field)
-            ++field_idx;
-          count = field_idx;
+          count = std::distance(record_decl->field_begin(),
+                                record_decl->field_end());
         }
       }
     }