add wchar header to the clang importer SDK

Author: hyp

test/Inputs/clang-importer-sdk/usr/include/wchar.h

@@ -0,0 +1,16 @@
+#ifndef _WCHAR_H_
+#define _WCHAR_H_
+
+typedef union {
+       char            __mbstate8[128];
+       long long       _mbstateL;                      /* for alignment */
+} __mbstate_t;
+
+typedef __mbstate_t mbstate_t;
+wchar_t        *wcschr(const wchar_t *, wchar_t);
+wchar_t        *wcspbrk(const wchar_t *, const wchar_t *);
+wchar_t        *wcsrchr(const wchar_t *, wchar_t);
+wchar_t        *wcsstr(const wchar_t * __restrict, const wchar_t * __restrict);
+wchar_t        *wmemchr(const wchar_t *, wchar_t, size_t);
+
+#endif /* !_WCHAR_H_ */