Fix fenv.pass.cpp signature for main

And make main return.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@356493 91177308-0d34-0410-b5e6-96231b3b80d8

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

@@ -14,6 +14,4 @@
 #error _LIBCPP_VERSION not defined
 #endif
 
-int main()
-{
-}
+int main(int, char**) { return 0; }