Fix Windows try_lock implementation

llvm-svn: 292011
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 08e1477ccbddb7fdf9998514c53844ef5db2f6e7
diff --git a/src/mutex.cpp b/src/mutex.cpp
index 9397ae7..338b79f 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -37,7 +37,7 @@
 bool
 mutex::try_lock() _NOEXCEPT
 {
-    return __libcpp_mutex_trylock(&__m_) == 0;
+    return __libcpp_mutex_trylock(&__m_);
 }
 
 void
@@ -83,7 +83,7 @@
 bool
 recursive_mutex::try_lock() _NOEXCEPT
 {
-    return __libcpp_recursive_mutex_trylock(&__m_) == 0;
+    return __libcpp_recursive_mutex_trylock(&__m_);
 }
 
 // timed_mutex