Fix invalid conversion from 'const char*' to 'char*' errors.

--- fam-2.7.0/src/NFSFileSystem.c++.orig	2010-01-05 12:35:34.347555169 -0200
+++ fam-2.7.0/src/NFSFileSystem.c++	2010-01-05 12:37:00.884679127 -0200
@@ -97,7 +97,7 @@ NFSFileSystem::NFSFileSystem(const mnten
 
     attr_cache_timeout = ACREGMAX;
 
-    char * p;
+    const char * p;
         
     if (strstr(opt, "noac")) {
         f_noac = true;