wininet: Allow a NULL value to be passed into HTTP_ProcessHeader instead of crashing so that when used with the replace flag it will delete an existing value.

[Robert Shearman]

---
  dlls/wininet/http.c |    2 ++
  1 files changed, 2 insertions(+), 0 deletions(-)
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diff --git a/dlls/wininet/http.c b/dlls/wininet/http.c
index 0eab832..c4c8fe4 100644
--- a/dlls/wininet/http.c
+++ b/dlls/wininet/http.c
@@ -2873,6 +2873,8 @@ static BOOL HTTP_ProcessHeader(LPWININET
 
         return HTTP_InsertCustomHeader(lpwhr, &hdr);
     }
+    /* no value to delete */
+    else return TRUE;
 
     if (dwModifier & HTTP_ADDHDR_FLAG_REQ)
 	    lphttpHdr->wFlags |= HDR_ISREQUEST;