urlmon: Constify some variables

[Andrew Talbot]

Changelog:
    urlmon: Constify some variables.

diff --git a/dlls/urlmon/format.c b/dlls/urlmon/format.c
index 0a0a97d..fdc0083 100644
--- a/dlls/urlmon/format.c
+++ b/dlls/urlmon/format.c
@@ -43,7 +43,7 @@ typedef struct {
     LONG ref;
 } EnumFORMATETC;
 
-static IEnumFORMATETC *EnumFORMATETC_Create(UINT cfmtetc, FORMATETC *rgfmtetc, UINT it);
+static IEnumFORMATETC *EnumFORMATETC_Create(UINT cfmtetc, const FORMATETC *rgfmtetc, UINT it);
 
 #define ENUMF_THIS(iface) ICOM_THIS_MULTI(EnumFORMATETC, lpEnumFORMATETCVtbl, iface)
 
@@ -158,7 +158,7 @@ static const IEnumFORMATETCVtbl EnumFORMATETCVtbl = {
     EnumFORMATETC_Clone
 };
 
-static IEnumFORMATETC *EnumFORMATETC_Create(UINT cfmtetc, FORMATETC *rgfmtetc, UINT it)
+static IEnumFORMATETC *EnumFORMATETC_Create(UINT cfmtetc, const FORMATETC *rgfmtetc, UINT it)
 {
     EnumFORMATETC *ret = HeapAlloc(GetProcessHeap(), 0, sizeof(EnumFORMATETC));
 
diff --git a/dlls/urlmon/http.c b/dlls/urlmon/http.c
index 89bdec3..46243e6 100644
--- a/dlls/urlmon/http.c
+++ b/dlls/urlmon/http.c
@@ -228,7 +228,7 @@ static void CALLBACK HTTPPROTOCOL_InternetStatusCallback(
     IInternetProtocolSink_ReportProgress(This->protocol_sink, ulStatusCode, (LPWSTR)lpvStatusInformation);
 }
 
-static inline LPWSTR strndupW(LPWSTR string, int len)
+static inline LPWSTR strndupW(LPCWSTR string, int len)
 {
     LPWSTR ret = NULL;
     if (string &&
diff --git a/dlls/urlmon/umon.c b/dlls/urlmon/umon.c
index 9d17afa..9cf1af3 100644
--- a/dlls/urlmon/umon.c
+++ b/dlls/urlmon/umon.c
@@ -183,7 +183,7 @@ static void Binding_CloseCacheDownload(Binding *This)
     This->pstrCache = 0;
 }
 
-static HRESULT Binding_MoreCacheData(Binding *This, char *buf, DWORD dwBytes)
+static HRESULT Binding_MoreCacheData(Binding *This, const char *buf, DWORD dwBytes)
 {
     DWORD written;