NOMMU: Optimise away the {dac_,}mmap_min_addr tests

In NOMMU mode clamp dac_mmap_min_addr to zero to cause the tests on it to be
skipped by the compiler.  We do this as the minimum mmap address doesn't make
any sense in NOMMU mode.

mmap_min_addr and round_hint_to_min() can be discarded entirely in NOMMU mode.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/mm/Kconfig b/mm/Kconfig
index 43ea8c3..ee9f3e0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -221,6 +221,7 @@
 
 config DEFAULT_MMAP_MIN_ADDR
         int "Low address space to protect from user allocation"
+	depends on MMU
         default 4096
         help
 	  This is the portion of low virtual memory which should be protected