Placate unused variable warnings uncovered by improvements to clang's -Wunused-variable

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@315809 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/depr/depr.c.headers/complex.h.pass.cpp

@@ -18,4 +18,5 @@
 int main()
 {
     std::complex<double> d;
+    (void)d;
 }

test/libcxx/depr/depr.c.headers/tgmath_h.pass.cpp

@@ -18,6 +18,7 @@
 int main()
 {
     std::complex<double> cd;
+    (void)cd;
     double x = sin(1.0);
     (void)x; // to placate scan-build
 }