vk/device: Mark newly allocated memory as undefined for valgrind
vk/device: Mark newly allocated memory as undefined for valgrind

This way valgrind still works even if the client gives us memory that has
been initialized or re-uses memory for some reason.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler