Fix warnings identified by clang

[taysta]

• (vk/engine) converts various sprintf() calls to com_sprintf()
• converts incorrtect sprintf() usage to q_strncpyz
• (rend2) fixes constructor parameter order
• (vk) fixes struct array member in boolean check always resulting in 'true'

note that most of these changes are not likely to result in a bugfix, just improved developer experience when compiling with clang, as these warnings will no longer be spammed in the build log.