ANDROID: mm: Fix implicit declaration of function 'isolate_lru_page'

When compiled with CONFIG_SHMEM=n, shmem.c does not include internal.h
and isolate_lru_page function declaration can't be found.
Fix this by making isolate_lru_page usage conditional upon CONFIG_SHMEM
inside reclaim_shmem_address_space.

Fixes: daeabfe7fa ("ANDROID: mm: add reclaim_shmem_address_space() for faster reclaims")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ia46a57681d26ac103e84ef7caa61a22dbd45cf04

mm/shmem.c

@@ -4307,6 +4307,7 @@ EXPORT_SYMBOL_GPL(shmem_mark_page_lazyfree);
 
 int reclaim_shmem_address_space(struct address_space *mapping)
 {
+#ifdef CONFIG_SHMEM
 	pgoff_t start = 0;
 	struct page *page;
 	LIST_HEAD(page_list);
@@ -4340,5 +4341,8 @@ int reclaim_shmem_address_space(struct address_space *mapping)
 	reclaimed = reclaim_pages_from_list(&page_list);
 
 	return reclaimed;
+#else
+	return 0;
+#endif
 }
 EXPORT_SYMBOL_GPL(reclaim_shmem_address_space);