findutils: needs mmu

Fix below build error:

./libfindtools.a(pred.o): In function `launch':
pred.c:(.text+0x240c): undefined reference to `fork'
collect2: .ld returned 1 exit status/libfindtools.a
(pred.o): In function `launch':
pred.c:(.text+0x240c): undefined reference to `fork'
collect2: ld returned 1 exit status
make[4]: *** [oldfind] Error 1
make[4]: *** Waiting for unfinished jobs....
make[4]: *** [find] Error 1

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/findutils/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_FINDUTILS
 	bool "findutils"
 	depends on BR2_USE_WCHAR
+	depends on BR2_USE_MMU # fork()
 	help
 	  Basic directory searching utilities.  Provides the
 	  common 'find', 'xargs', 'locate', and 'updatedb' binaries.