VulkanBenchmarks: fix memory leaks
VulkanBenchmarks: fix memory leaks

Found these leaks using AppVerifier on Windows.

Bug: b/176981107
Change-Id: I89cbfc02e6adf0ea2a54cf80501fbbb3d0867964
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/51748
Reviewed-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Tested-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>
Commit-Queue: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>

google/swiftshader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader