Add RtlAnsiCharToUnicodeChar definition.
Correct stub status of RtlAnsiCharToUnicodeChar.

dlls/ntdll/ntdll.spec

diff --git a/dlls/ntdll/ntdll.spec b/dlls/ntdll/ntdll.spec
index d8e1594..c18b8c6 100644
--- a/dlls/ntdll/ntdll.spec
+++ b/dlls/ntdll/ntdll.spec
@@ -304,7 +304,7 @@
 @ stdcall RtlAllocateAndInitializeSid (ptr long long long long long long long long long ptr)
 @ stdcall RtlAllocateHandle(ptr ptr)
 @ stdcall RtlAllocateHeap(long long long)
-@ stub RtlAnsiCharToUnicodeChar
+@ stdcall RtlAnsiCharToUnicodeChar(ptr)
 @ stdcall RtlAnsiStringToUnicodeSize(ptr)
 @ stdcall RtlAnsiStringToUnicodeString(ptr ptr long)
 @ stdcall RtlAppendAsciizToString(ptr str)

include/winternl.h

diff --git a/include/winternl.h b/include/winternl.h
index c8740d6..aefa336 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -1617,6 +1617,7 @@
 NTSTATUS  WINAPI RtlAllocateAndInitializeSid(PSID_IDENTIFIER_AUTHORITY,BYTE,DWORD,DWORD,DWORD,DWORD,DWORD,DWORD,DWORD,DWORD,PSID *);
 RTL_HANDLE * WINAPI RtlAllocateHandle(RTL_HANDLE_TABLE *,ULONG *);
 PVOID     WINAPI RtlAllocateHeap(HANDLE,ULONG,ULONG);
+WCHAR     WINAPI RtlAnsiCharToUnicodeChar(LPSTR *);
 DWORD     WINAPI RtlAnsiStringToUnicodeSize(const STRING *);
 NTSTATUS  WINAPI RtlAnsiStringToUnicodeString(PUNICODE_STRING,PCANSI_STRING,BOOLEAN);
 NTSTATUS  WINAPI RtlAppendAsciizToString(STRING *,LPCSTR);