GH-35186: [CI][C++] Improve GoogleTest detection on Windows + vcpkg (#…

…35200)

### Rationale for this change

We must be able to use GoogleTest installed by vcpkg on Windows.

### What changes are included in this PR?

Add missing `-DCMAKE_CXX_STANDARD`.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

Yes.
* Closes: #35186

Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Raúl Cumplido <raulcumplido@gmail.com>

cpp/cmake_modules/FindGTestAlt.cmake

@@ -52,11 +52,14 @@ TEST(CXX_STANDARD, MatcherStringView) {
        ")
   try_compile(GTestAlt_CXX_STANDARD_AVAILABLE ${CMAKE_CURRENT_BINARY_DIR}
               SOURCES ${GTestAlt_CXX_STANDARD_TEST_SOURCE}
-              LINK_LIBRARIES GTest::gtest_main)
+              CMAKE_FLAGS "-DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}"
+              LINK_LIBRARIES GTest::gtest_main
+              OUTPUT_VARIABLE GTestAlt_CXX_STANDARD_OUTPUT)
   set(CMAKE_TRY_COMPILE_TARGET_TYPE ${KEEP_CMAKE_TRY_COMPILE_TARGET_TYPE})
   if(NOT GTestAlt_CXX_STANDARD_AVAILABLE)
-    message(STATUS "GTest can't be used with C++${CMAKE_CXX_STANDARD}. Use -DGTest_SOURCE=BUNDLED."
-    )
+    message(STATUS "GTest can't be used with C++${CMAKE_CXX_STANDARD}.")
+    message(STATUS "Use -DGTest_SOURCE=BUNDLED.")
+    message(STATUS "Output:\n${GTestAlt_CXX_STANDARD_OUTPUT}")
     find_package_handle_standard_args(GTestAlt
                                       REQUIRED_VARS GTestAlt_CXX_STANDARD_AVAILABLE)
   endif()