advapi32: Constify a variable

[Andrew Talbot]

Changelog:
    advapi32: Constify a variable.

diff -urN a/dlls/advapi32/crypt.c b/dlls/advapi32/crypt.c
--- a/dlls/advapi32/crypt.c	2007-02-05 17:39:16.000000000 +0000
+++ b/dlls/advapi32/crypt.c	2007-03-03 22:29:09.000000000 +0000
@@ -193,7 +193,7 @@
 	if ( !(provider->pFuncs->p##name = (void*)GetProcAddress(provider->hModule, #name)) ) goto error
 #define CRYPT_GetProvFuncOpt(name) \
 	provider->pFuncs->p##name = (void*)GetProcAddress(provider->hModule, #name)
-static PCRYPTPROV CRYPT_LoadProvider(PWSTR pImage)
+static PCRYPTPROV CRYPT_LoadProvider(PCWSTR pImage)
 {
 	PCRYPTPROV provider;
 	DWORD errorcode = ERROR_NOT_ENOUGH_MEMORY;