LibAudio: Add the Int32 sample format

The signed 32-bit PCM sample format is required for the FLAC standard.

Userland/Libraries/LibAudio/Buffer.cpp

@@ -21,6 +21,7 @@ u16 pcm_bits_per_sample(PcmSampleFormat format)
         return 16;
     case Int24:
         return 24;
+    case Int32:
     case Float32:
         return 32;
     case Float64:

Userland/Libraries/LibAudio/Buffer.h

@@ -76,6 +76,7 @@ enum PcmSampleFormat : u8 {
     Uint8,
     Int16,
     Int24,
+    Int32,
     Float32,
     Float64,
 };