avifil32: Constify some variables

[Andrew Talbot]

Changelog:
    avifil32: Constify some variables.

diff -urN a/dlls/avifil32/extrachunk.c b/dlls/avifil32/extrachunk.c
--- a/dlls/avifil32/extrachunk.c	2006-10-25 17:33:22.000000000 +0100
+++ b/dlls/avifil32/extrachunk.c	2007-03-13 21:14:18.000000000 +0000
@@ -29,8 +29,7 @@
 WINE_DEFAULT_DEBUG_CHANNEL(avifile);
 
 /* reads a chunk outof the extrachunk-structure */
-HRESULT ReadExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lpData,
-		       LPLONG size)
+HRESULT ReadExtraChunk(const LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lpData,LPLONG size)
 {
   LPBYTE lp;
   DWORD  cb;
@@ -68,8 +67,7 @@
 }
 
 /* writes a chunk into the extrachunk-structure */
-HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lpData,
-			LONG size)
+HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPCVOID lpData, LONG size)
 {
   LPDWORD lp;
 
diff -urN a/dlls/avifil32/extrachunk.h b/dlls/avifil32/extrachunk.h
--- a/dlls/avifil32/extrachunk.h	2006-05-23 13:47:33.000000000 +0100
+++ b/dlls/avifil32/extrachunk.h	2007-03-13 21:10:48.000000000 +0000
@@ -35,10 +35,10 @@
 } EXTRACHUNKS, *LPEXTRACHUNKS;
 
 /* reads a chunk outof the extrachunk-structure */
-HRESULT ReadExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lp,LPLONG size);
+HRESULT ReadExtraChunk(const LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lp,LPLONG size);
 
 /* writes a chunk into the extrachunk-structure */
-HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lp,LONG size);
+HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPCVOID lp,LONG size);
 
 /* reads a chunk fomr the HMMIO into the extrachunk-structure */
 HRESULT ReadChunkIntoExtra(LPEXTRACHUNKS extra,HMMIO hmmio,MMCKINFO *lpck);