memory: exit when hugepage allocation fails if mem-prealloc

When -mem-prealloc is passed on the command-line, the expected
behavior is to exit if the hugepage allocation fails.  However,
this behavior is broken since commit cc57501d which made
hugepage allocation fall back to regular ram in case of faliure.

This commit restores the expected behavior for -mem-prealloc.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Message-Id: <20160122091501.75bbd42a@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

numa.c

@@ -418,12 +418,15 @@ static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner,
         Error *err = NULL;
         memory_region_init_ram_from_file(mr, owner, name, ram_size, false,
                                          mem_path, &err);
-
-        /* Legacy behavior: if allocation failed, fall back to
-         * regular RAM allocation.
-         */
         if (err) {
             error_report_err(err);
+            if (mem_prealloc) {
+                exit(1);
+            }
+
+            /* Legacy behavior: if allocation failed, fall back to
+             * regular RAM allocation.
+             */
             memory_region_init_ram(mr, owner, name, ram_size, &error_fatal);
         }
 #else