Fix build on MinGW

Original downstream patch by Tom Ritter <tom@mozilla.com>.

CMakeLists.txt

@@ -259,7 +259,7 @@ if(USE_WASAPI)
   target_sources(cubeb PRIVATE
     src/cubeb_wasapi.cpp)
   target_compile_definitions(cubeb PRIVATE USE_WASAPI)
-  target_link_libraries(cubeb PRIVATE avrt ole32)
+  target_link_libraries(cubeb PRIVATE avrt ole32 ksuser)
 endif()
 
 check_include_files("windows.h;mmsystem.h" USE_WINMM)

src/cubeb_winmm.c

@@ -73,17 +73,6 @@
 #define CUBEB_STREAM_MAX 32
 #define NBUFS 4
 
-const GUID KSDATAFORMAT_SUBTYPE_PCM = {
-    0x00000001,
-    0x0000,
-    0x0010,
-    {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}};
-const GUID KSDATAFORMAT_SUBTYPE_IEEE_FLOAT = {
-    0x00000003,
-    0x0000,
-    0x0010,
-    {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}};
-
 struct cubeb_stream_item {
   SLIST_ENTRY head;
   cubeb_stream * stream;