Fix unused variables in tests to placate scan-build. Patch from Steve MacKenzie.

llvm-svn: 220154
diff --git a/libcxx/test/depr/depr.c.headers/tgmath_h.pass.cpp b/libcxx/test/depr/depr.c.headers/tgmath_h.pass.cpp
index c4c9e85..a2ef814 100644
--- a/libcxx/test/depr/depr.c.headers/tgmath_h.pass.cpp
+++ b/libcxx/test/depr/depr.c.headers/tgmath_h.pass.cpp
@@ -19,4 +19,5 @@
 {
     std::complex<double> cd;
     double x = sin(1.0);
+    (void)x; // to placate scan-build
 }