Add memory compatibility wrappers

The function vmem_qcache_reap() and global variables 'needfree',
'desfree', and 'lotsfree' are all used in the upstream.  While
these variables have no meaning under Linux they're being defined
as 0's to avoid needing to make additional changes to the ARC code.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

include/sys/vmem.h

@@ -98,6 +98,7 @@ extern void *spl_vmalloc(unsigned long size, gfp_t lflags, pgprot_t prot);
 #define	vmem_alloc(sz, fl)	spl_vmem_alloc((sz), (fl), __func__, __LINE__)
 #define	vmem_zalloc(sz, fl)	spl_vmem_zalloc((sz), (fl), __func__, __LINE__)
 #define	vmem_free(ptr, sz)	spl_vmem_free((ptr), (sz))
+#define	vmem_qcache_reap(ptr)	((void)0)
 
 extern void *spl_vmem_alloc(size_t sz, int fl, const char *func, int line);
 extern void *spl_vmem_zalloc(size_t sz, int fl, const char *func, int line);

include/sys/vmsystm.h

@@ -36,6 +36,9 @@
 #define	membar_producer()		smp_wmb()
 #define	physmem				totalram_pages
 #define	freemem				nr_free_pages()
+#define	needfree			0
+#define	desfree				0
+#define	lotsfree			0
 
 #define	xcopyin(from, to, size)		copy_from_user(to, from, size)
 #define	xcopyout(from, to, size)	copy_to_user(to, from, size)