CheckSymbolExists: Avoid removing the flag after -Werror In commit 1ab7c3cd28 (CheckSymbolExists: Work around GCC failure with -pedantic-errors option, 2021-10-22, v3.23.0-rc1~498^2) we used the same code that was fixed by commit cec6f98018 (CMakeDetermineCompilerABI: Avoid removing the flag after -Werror, 2023-05-29, v3.26.5~4^2). Apply the fix to CheckSymbolExists too.