`std::is_pod<T>` was deprecated in C++20
original (pre `is_pod`) error on GCC 4.8:
```
/fmt/test/gtest/gtest.h: In static member function 'static constexpr bool testing::internal::MatcherBase<T>::IsInlined()':
/fmt/test/gtest/gtest.h:6512:12: error: 'is_trivially_copy_constructible' was not declared in this scope
std::is_trivially_copy_constructible<M>::value &&
^
/fmt/test/gtest/gtest.h:6512:45: error: expected primary-expression before '>' token
std::is_trivially_copy_constructible<M>::value &&
^
/fmt/test/gtest/gtest.h:6512:46: error: '::value' has not been declared
std::is_trivially_copy_constructible<M>::value &&
^
```
* all GTest/GMock files moved to `test/gtest` directory
* `CMakeLists.txt` created in `test/gtest` from `CMakeLists.txt` in `test`
* GTest/GMock target in CMake renamed to `gtest` (was `gmock`)
* CMake `gtest` target updated to export includes as "gtest/gtest.h" or "gmock/gmock.h" only
* includes in tests updated: "gtest.h" -> "gtest/gtest.h", "gmock.h" -> "gmock/gmock.h"
* removed duplications of `target_include_directories` for GTest/GMock directories (CMake manages them)
* find-package-test fixed by passing CXX_FLAGS, i.e. -stdlib=libc++
* std::array usage in compile-test.cc replaced with plain array, because
<array> header was not included
- Fix C++17 Visual Studio builds.
- Use C++17 for `windows-2019` builds.
- Removed options for unsupported compiler (MSVC11).
- Removed options, not needed after enabling C++11+ features in gmock/gtest.
* Don't include <cassert>. (#2148)
This commit replaces use of the assert() macro in format-inl.h with
FMT_ASSERT(). This allows us to drop the cassert include.
* FMT_GCC_VERSION is not defined when we include test-assert.h, use __GCC__ instead.
* Don't explicitly suppress GCC's -Wterminate in tests' FMT_ASSERT.
Throwing from a separate function is enough to silence the warning, no need to
explicitly suppress it.
* Remove messages from assertions added in 2f699d2.
* Correct formatting around throw_assertion_failure().
* fix fallback to the runtime API, add FMT_ENABLE_FALLBACK_TO_RUNTIME_API define, add test
* remove `FMT_ENABLE_FALLBACK_TO_RUNTIME_API`
* pass format string to format_to() inside format_to_n() in compile-time API
instead of compiling it inside format_to_n(), to eliminate code duplication
