Altered boinc_fopen() to use _fsopen() under _WIN32 with the sharing

flags set to the most permissive value.  This may solve some virus
scanner locking problems.

svn path=/trunk/boinc/; revision=9860

lib/filesys.C

@@ -371,7 +371,7 @@ FILE* boinc_fopen(const char* path, const char* mode) {
     if (!f) {
         for (int i=0; i<5; i++) {
             boinc_sleep(drand());
-            f = fopen(path, mode);
+            f = _fsopen(path, mode, _SH_DENYNO);
             if (f) break;
         }
     }