Fix / suppress new unused warnings for mingw+clang

Bug: 69933068
Test: mmma system/core
Change-Id: I089166a979d3d8c5ada38a7745d507b555048499
diff --git a/libutils/Threads.cpp b/libutils/Threads.cpp
index 6317c32..7d7f0e2 100644
--- a/libutils/Threads.cpp
+++ b/libutils/Threads.cpp
@@ -348,7 +348,7 @@
     mState = (void*) hMutex;
 }
 
-Mutex::Mutex(const char* name)
+Mutex::Mutex(const char* /*name*/)
 {
     // XXX: name not used for now
     HANDLE hMutex;
@@ -359,7 +359,7 @@
     mState = (void*) hMutex;
 }
 
-Mutex::Mutex(int type, const char* name)
+Mutex::Mutex(int /*type*/, const char* /*name*/)
 {
     // XXX: type and name not used for now
     HANDLE hMutex;