Split <stdio.h> out of <cstdio>.

As with <stddef.h>, skip our custom header if __need_FILE or __need___FILE is defined.

llvm-svn: 249798
diff --git a/libcxx/test/std/depr/depr.c.headers/stdio_h.pass.cpp b/libcxx/test/std/depr/depr.c.headers/stdio_h.pass.cpp
index ba6714d..3c5dd0e 100644
--- a/libcxx/test/std/depr/depr.c.headers/stdio_h.pass.cpp
+++ b/libcxx/test/std/depr/depr.c.headers/stdio_h.pass.cpp
@@ -13,6 +13,26 @@
 #include <type_traits>
 #include "test_macros.h"
 
+#ifdef getc
+#error getc is defined
+#endif
+
+#ifdef putc
+#error putc is defined
+#endif
+
+#ifdef clearerr
+#error clearerr is defined
+#endif
+
+#ifdef feof
+#error feof is defined
+#endif
+
+#ifdef ferror
+#error ferror is defined
+#endif
+
 #ifndef BUFSIZ
 #error BUFSIZ not defined
 #endif