Benchmark time spent by all threads

Google Benchmark by default only measures time spent in the main thread.
Since our Vulkan queue implementation executes command buffers on a
separate thread, this can lead to very little "CPU" time being
reported. Use MeasureProcessCPUTime() instead to use the total CPU usage
of the process by all the threads: https://github.com/google/benchmark#cpu-timers

Bug: b/177624844
Change-Id: I071cd31095a83a5afec51120fb78e42decda2083
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52628
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Commit-Queue: Nicolas Capens <nicolascapens@google.com>

tests/VulkanBenchmarks/ClearImageBenchmarks.cpp

diff --git a/tests/VulkanBenchmarks/ClearImageBenchmarks.cpp b/tests/VulkanBenchmarks/ClearImageBenchmarks.cpp
index 36d0449..8852903 100644
--- a/tests/VulkanBenchmarks/ClearImageBenchmarks.cpp
+++ b/tests/VulkanBenchmarks/ClearImageBenchmarks.cpp
@@ -138,6 +138,6 @@
 	}
 }
 
-BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_R8G8B8A8_UNORM, vk::Format::eR8G8B8A8Unorm, vk::ImageAspectFlagBits::eColor)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_R32_SFLOAT, vk::Format::eR32Sfloat, vk::ImageAspectFlagBits::eColor)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_D32_SFLOAT, vk::Format::eD32Sfloat, vk::ImageAspectFlagBits::eDepth)->Unit(benchmark::kMillisecond);
+BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_R8G8B8A8_UNORM, vk::Format::eR8G8B8A8Unorm, vk::ImageAspectFlagBits::eColor)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_R32_SFLOAT, vk::Format::eR32Sfloat, vk::ImageAspectFlagBits::eColor)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(ClearImage, VK_FORMAT_D32_SFLOAT, vk::Format::eD32Sfloat, vk::ImageAspectFlagBits::eDepth)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();

tests/VulkanBenchmarks/TriangleBenchmarks.cpp

diff --git a/tests/VulkanBenchmarks/TriangleBenchmarks.cpp b/tests/VulkanBenchmarks/TriangleBenchmarks.cpp
index fc342a9..215d3f4 100644
--- a/tests/VulkanBenchmarks/TriangleBenchmarks.cpp
+++ b/tests/VulkanBenchmarks/TriangleBenchmarks.cpp
@@ -271,9 +271,9 @@
 	RunBenchmark(state, tester);
 }
 
-BENCHMARK_CAPTURE(TriangleSolidColor, TriangleSolidColor, Multisample::False)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(TriangleInterpolateColor, TriangleInterpolateColor, Multisample::False)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(TriangleSampleTexture, TriangleSampleTexture, Multisample::False)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(TriangleSolidColor, TriangleSolidColor_Multisample, Multisample::True)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(TriangleInterpolateColor, TriangleInterpolateColor_Multisample, Multisample::True)->Unit(benchmark::kMillisecond);
-BENCHMARK_CAPTURE(TriangleSampleTexture, TriangleSampleTexture_Multisample, Multisample::True)->Unit(benchmark::kMillisecond);
+BENCHMARK_CAPTURE(TriangleSolidColor, TriangleSolidColor, Multisample::False)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(TriangleInterpolateColor, TriangleInterpolateColor, Multisample::False)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(TriangleSampleTexture, TriangleSampleTexture, Multisample::False)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(TriangleSolidColor, TriangleSolidColor_Multisample, Multisample::True)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(TriangleInterpolateColor, TriangleInterpolateColor_Multisample, Multisample::True)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();
+BENCHMARK_CAPTURE(TriangleSampleTexture, TriangleSampleTexture_Multisample, Multisample::True)->Unit(benchmark::kMillisecond)->MeasureProcessCPUTime();