vulkan: rework driver::Get*ProcAddr

Introduce driver::ProcHook which is a struct to describe an intercepted
function.  Given a function name, GetProcHook returns a ProcHook if the
function is intercepted.  NULL otherwise.

A ProcHook has three function pointers.  ProcHook::proc points to the real
intercepting function.  ProcHook::disabled_proc points to a no-op function
that logs an error.  ProcHook::checked_proc points to a trampoline that
calls either ProcHook::proc or ProcHook::disabled_proc.

For core functions, driver::Get*ProcAddr simply return ProcHook::proc.
For extension functions, driver::Get*ProcAddr return ProcHook::proc when
the extension is known to be enabled.  They return ProcHook::disabled_proc
when the extension is known to be disabled.  Finally, they return
ProcHook::checked_proc when they do not know if the extension is enabled
or not.

All ProcHooks as well as their disabled_proc/checked_proc are generated in
driver_gen.cpp.  This allows us to get rid of all hand-written "_Disabled"
functions, all no-op "_Bottom" functions, and special cases for
VK_ANDROID_native_buffer.  The reworked driver::Get*ProcAddr also detects
more applications' errors and logs them.

Change-Id: I8e6f476f450688b5547fd75243c66cb603c516b5