[LibOS] Return rlim_max = RLIM_INFINITY in getrlimit(RLIMIT_DATA)

RLIMIT_DATA must return a max memory address such that if this limit is
exceeded, the malloc() function shall fail with errno = ENOMEM. Since
Graphene does not have a strict limit on max memory range in VMAs, set
the limit to RLIM_INFINITY.

LibOS/shim/src/sys/shim_getrlimit.c

@@ -57,7 +57,7 @@ int shim_do_getrlimit (int resource, struct __kernel_rlimit * rlim)
 
         case RLIMIT_DATA:
             rlim->rlim_cur = brk_max_size;
-            rlim->rlim_max = brk_max_size;
+            rlim->rlim_max = RLIM_INFINITY;
             return 0;
 
         default: