[lldb] Use std::tie to implement operator< (NFC) (#141416)

Author: kazutakahirata

lldb/include/lldb/Symbol/CompilerDeclContext.h

@@ -48,9 +48,8 @@ class CompilerDeclContext {
   explicit operator bool() const { return IsValid(); }
 
   bool operator<(const CompilerDeclContext &rhs) const {
-    if (m_type_system == rhs.m_type_system)
-      return m_opaque_decl_ctx < rhs.m_opaque_decl_ctx;
-    return m_type_system < rhs.m_type_system;
+    return std::tie(m_type_system, m_opaque_decl_ctx) <
+           std::tie(rhs.m_type_system, rhs.m_opaque_decl_ctx);
   }
 
   bool IsValid() const {

lldb/include/lldb/Target/CoreFileMemoryRanges.h

@@ -30,11 +30,8 @@ struct CoreFileMemoryRange {
   }
 
   bool operator<(const CoreFileMemoryRange &rhs) const {
-    if (range < rhs.range)
-      return true;
-    if (range == rhs.range)
-      return lldb_permissions < rhs.lldb_permissions;
-    return false;
+    return std::tie(range, lldb_permissions) <
+           std::tie(rhs.range, rhs.lldb_permissions);
   }
 
   std::string Dump() const {

lldb/source/Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h

@@ -386,16 +386,8 @@ class ObjCLanguageRuntime : public LanguageRuntime {
     }
 
     bool operator<(const ClassAndSel &rhs) const {
-      if (class_addr < rhs.class_addr)
-        return true;
-      else if (class_addr > rhs.class_addr)
-        return false;
-      else {
-        if (sel_addr < rhs.sel_addr)
-          return true;
-        else
-          return false;
-      }
+      return std::tie(class_addr, sel_addr) <
+             std::tie(rhs.class_addr, rhs.sel_addr);
     }
 
     lldb::addr_t class_addr = LLDB_INVALID_ADDRESS;