tools/elfutils: depend on m4

Some buildbots fail to build elfutils due to m4 being missing. Add m4 as
a dependency for elfutils to fix this.

Fixes: ad79b9271949 ("elfutils: move host build to tools")
Signed-off-by: Stijn Tintel <[email protected]>

tools/Makefile

@@ -85,7 +85,7 @@ ifeq ($(HOST_OS),Darwin)
   tools-y += bash
 else
   $(curdir)/dwarves/compile += $(curdir)/elfutils/compile
-  $(curdir)/elfutils/compile := $(curdir)/zlib/compile
+  $(curdir)/elfutils/compile := $(curdir)/m4/compile $(curdir)/zlib/compile
   tools-$(CONFIG_DWARVES) += dwarves
   tools-y += elfutils
 endif