Merge #18882: build: fix -Wformat-security check when compiling with GCC

6cef3652d143a1dddad1254cab0953561d24c1fa build: fix -Wformat-security check when compiling with GCC (fanquake)

Pull request description:

  GCC expects `-Wformat` to be passed with [`-Wformat-security`](https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html), which means
  when we test for it in configure it currently fails:

  ```bash
  checking whether C++ compiler accepts -Wformat-security... no
  ...
  configure:15907: checking whether C++ compiler accepts -Wformat-security
  configure:15926: g++ -std=c++11 -c -g -O2 -Werror -Wformat-security  conftest.cpp >&5
  cc1plus: error: '-Wformat-security' ignored without '-Wformat' [-Werror=format-security]
  cc1plus: all warnings being treated as errors
  ```

  and never gets added to our CXX flags. Note that Clang does not have this requirement and the check is working correctly there.

  The change in this PR is the simple fix, however we might want to consider using something like `-Wformat=2` in future, which in GCC is equivalent to `-Wformat -Wformat-nonliteral -Wformat-security -Wformat-y2k.` and similar [in Clang](https://clang.llvm.org/docs/DiagnosticsReference.html#wformat-2).

ACKs for top commit:
  practicalswift:
    ACK 6cef3652d143a1dddad1254cab0953561d24c1fa
  laanwj:
    ACK 6cef3652d143a1dddad1254cab0953561d24c1fa

Tree-SHA512: f9230d42af39f85ea9d2f55dbbebd2bae4740fe59b0da2e092af3ac9ef7e6799d3a4cf83eb64574c63982e5f6b14e226d44c84fa0335255d65c9947d86a1ea38

0 files changed, 0 insertions, 0 deletions