fix compatible issue with gcc-9 #466

Job	Run time
aarch64	1m 43s
cmake	1m 34s
arenastring-gcc-stdlibc++-default	1m 39s
arenastring-gcc-stdlibc++-half	1m 37s
basic-gcc-dbg-c++20-stdlibc++-asan	1m 50s
arenastring-gcc-stdlibc++-full	1m 45s
basic-gcc-dbg-c++20-stdlibc++-tsan	1m 31s
compatible-gcc-9	9m 1s
arenastring-clang-stdlibc++-default	1m 56s
basic-gcc-dbg-c++14-stdlibc++-asan	1m 21s
coverage	1m 33s
arenastring-clang-libc++-default	2m 4s
basic-gcc-opt-c++20-stdlibc++-asan	1m 51s
cpp14-coroutine	1m 15s
basic-gcc-opt-c++20-stdlibc++-tsan	1m 40s
workspace	59s
basic-gcc-opt-c++14-stdlibc++-asan	1m 31s
basic-clang-dbg-c++20-stdlibc++-asan	1m 43s
basic-clang-dbg-c++20-stdlibc++-tsan	1m 55s
basic-clang-dbg-c++20-libc++-asan	2m 13s
basic-clang-dbg-c++20-libc++-tsan	2m 14s
basic-clang-dbg-c++14-stdlibc++-asan	1m 34s
basic-clang-dbg-c++14-libc++-asan	1m 39s
basic-clang-opt-c++20-stdlibc++-asan	1m 51s
basic-clang-opt-c++20-stdlibc++-tsan	1m 55s
basic-clang-opt-c++20-libc++-asan	2m 7s
basic-clang-opt-c++20-libc++-tsan	1m 53s
basic-clang-opt-c++14-stdlibc++-asan	1m 55s
basic-clang-opt-c++14-libc++-asan	1m 55s
	57m 44s

Provide feedback