use much faster exp2/cos approximations in ffmpeg, large decrease in cpu usage on my machine on decoder thread

properly byteswap r13 for spinlock
Add PPCOpcodeBits
stub out broken fpscr updating in ppc_hir_builder. it's just code that repeatedly does nothing right now.
add note about 0 opcode bytes being executed to ppc_frontend
Add assert to check that function end is greater than function start, can happen with malformed functions
Disable prefetch and cachecontrol by default, automatic hardware prefetchers already do the job for the most part
minor cleanup in simplification_pass, dont loop optimizations, let the pass manager do it for us
Add experimental "delay_via_maybeyield" cvar, which uses MaybeYield to "emulate" the db16cyc instruction
Add much faster/simpler way of directly calling guest functions, no longer have to do a byte by byte search through the generated code
Generate label string ids on the fly
Fix unused function warnings for prefetch on clang, fix many other clang warnings
Eliminated majority of CallNativeSafes by replacing them with naive generic code paths.
^ Vector rotate left, vector shift left, vector shift right, vector shift arithmetic right, and vector average are included
These naive paths are implemented small loops that stash the two inputs to the stack and load them in gprs from there, they are not particularly fast but should be an order of magnitude faster than callnativesafe
to a host function, which would involve a call, stashing all volatile registers, an indirect call, potentially setting up a stack frame for the arrays that the inputs get stashed to, the actual operations, a return, loading all volatile registers, a return, etc
Added the fast SHR_V128 path back in
Implement signed vector average byte, signed vector average word. previously we were emitting no code for them. signed vector average byte appears in many games
Fix bug with signed vector average 32, we were doing unsigned shift, turning negative values into big positive ones potentially

src/xenia/base/threading_win.cc

@@ -117,7 +117,7 @@ void set_name(const std::string_view name) {
 
 // checked ntoskrnl, it does not modify delay, so we can place this as a
 // constant and avoid creating a stack variable
-static const LARGE_INTEGER sleepdelay0_for_maybeyield{0LL};
+static const LARGE_INTEGER sleepdelay0_for_maybeyield{{0LL}};
 
 void MaybeYield() {
 #if 0
@@ -314,7 +314,8 @@ class Win32Event : public Win32Handle<Event> {
   }
 #endif
 
-  EventInfo Query() { EventInfo result{};
+  EventInfo Query() override {
+    EventInfo result{};
     NtQueryEventPointer.invoke(handle_, 0, &result, sizeof(EventInfo), nullptr);
     return result;
   }
@@ -429,7 +430,7 @@ class Win32Timer : public Win32Handle<Timer> {
   }
   bool SetRepeatingAt(GClock_::time_point due_time,
                       std::chrono::milliseconds period,
-                      std::function<void()> opt_callback = nullptr) {
+                      std::function<void()> opt_callback = nullptr) override {
     return SetRepeatingAt(date::clock_cast<WClock_>(due_time), period,
                           std::move(opt_callback));
   }