libunwind: enable build for arm

Tested with perf on mvebu.

Signed-off-by: Maxim Gorbachyov <maxim.gorbachyov@gmail.com>

package/libs/libunwind/Makefile

@@ -32,7 +32,7 @@ define Package/libunwind
   CATEGORY:=Libraries
   TITLE:=The libunwind project
   URL:=http://www.nongnu.org/libunwind/
-  DEPENDS:=@(mips||mipsel||powerpc||i386||x86_64)
+  DEPENDS:=@(mips||mipsel||powerpc||i386||x86_64||arm)
 endef
 
 define Package/libunwind/description