linux, audio: add hooks acmFormatSuggest (#455)

## Link to GitHub Issue, if one exists
n/a

## Description of change

`acmFormatSuggest` is known to cause significant perf issues on Linux;
add a hook to return cached results.

The fix is only active in the Linux variant.

For discussion, see
* https://codeberg.org/nixac/spicetools/issues/2
* https://codeberg.org/nixac/spicetools/issues/4

## Testing
I've only tested this on Windows, checking if iidx and popn can boot,
play songs without audio issues.

src/spice2x/hooks/audio/audio.cpp

@@ -13,6 +13,7 @@
 #include "util/memutils.h"
 
 #include "audio_private.h"
+#include "acm.h"
 
 #ifdef _MSC_VER
 DEFINE_GUID(CLSID_MMDeviceEnumerator,
@@ -101,6 +102,7 @@ namespace hooks::audio {
 
         log_info("audio", "initializing");
         init_low_latency();
+        hooks::audio::acm::init();
 
         // general hooks
         CoCreateInstance_orig = detour::iat_try("CoCreateInstance", CoCreateInstance_hook);