[ExecutionEngine] Avoid repeated hash lookups (NFC) (#109563)

Author: kazutakahirata

llvm/lib/ExecutionEngine/JITLink/DefineExternalSectionStartAndEndSymbols.h

@@ -71,10 +71,7 @@ class DefineExternalSectionStartAndEndSymbols {
 
 private:
   SectionRange &getSectionRange(Section &Sec) {
-    auto I = SectionRanges.find(&Sec);
-    if (I == SectionRanges.end())
-      I = SectionRanges.insert(std::make_pair(&Sec, SectionRange(Sec))).first;
-    return I->second;
+    return SectionRanges.try_emplace(&Sec, Sec).first->second;
   }
 
   DenseMap<Section *, SectionRange> SectionRanges;