Added return reference from stack::emplace #522

Job	Run time
Syntax Check - Clang C++03 Linux STL (ubuntu-22.04)	26s
Syntax Check - Clang C++03 Linux No STL (ubuntu-22.04)	23s
Syntax Check - Clang C++11 Linux No STL (ubuntu-22.04)	36s
Syntax Check - Clang C++11 Linux No STL Force C++03 (ubuntu-22.04)	35s
Syntax Check - Clang C++11 Linux STL (ubuntu-22.04)	48s
Syntax Check - Clang C++11 Linux STL Force C++03 (ubuntu-22.04)	37s
Syntax Check - Clang C++14 Linux No STL (ubuntu-22.04)	36s
Syntax Check - Clang C++14 Linux No STL Force C++03 (ubuntu-22.04)	35s
Syntax Check - Clang C++14 Linux STL (ubuntu-22.04)	39s
Syntax Check - Clang C++14 Linux STL Force C++03 (ubuntu-22.04)	39s
Syntax Check - Clang C++17 Linux No STL (ubuntu-22.04)	42s
Syntax Check - Clang C++17 Linux No STL Force C++03 (ubuntu-22.04)	47s
Syntax Check - Clang C++17 Linux STL (ubuntu-22.04)	56s
Syntax Check - Clang C++17 Linux STL Force C++03 (ubuntu-22.04)	52s
Syntax Check - Clang C++20 Linux No STL (ubuntu-22.04)	1m 2s
Syntax Check - Clang C++20 Linux STL (ubuntu-22.04)	1m 15s
Syntax Check - Clang C++20 Linux STL Force C++03 (ubuntu-22.04)	1m 28s
Syntax Check - Clang C++20 Linux No STL Force C++03 (ubuntu-22.04)	1m 3s
	13m 59s

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