[libc][obvious] Fixed typos in some wchar headers (#146413)

Some of the wchar headers had typos in them.

Co-authored-by: Sriya Pratipati <sriyap@google.com>

libc/src/wchar/wcpncpy.h

@@ -20,4 +20,4 @@ wchar_t *wcpncpy(wchar_t *__restrict ws1, const wchar_t *__restrict ws2,
 
 } // namespace LIBC_NAMESPACE_DECL
 
-#endif // LLVM_LIBC_SRC_WCHAR_WCPNsCPY_H
+#endif // LLVM_LIBC_SRC_WCHAR_WCPNCPY_H

libc/src/wchar/wcsspn.h

@@ -19,4 +19,4 @@ size_t wcsspn(const wchar_t *s1, const wchar_t *s2);
 
 } // namespace LIBC_NAMESPACE_DECL
 
-#endif // LLVM_LIBC_SRC_WCHAR_WCSCHR_H
+#endif // LLVM_LIBC_SRC_WCHAR_WCSSPN_H