tools/genext2fs: Add dependency to libtool

This fixes the following build error:
  ./autogen.sh: line 13: aclocal: command not found

Fixes: b6d29af9475f ("tools/genext2fs: update to 1.5.0")
Signed-off-by: Hauke Mehrtens <[email protected]>

tools/Makefile

@@ -52,6 +52,7 @@ $(curdir)/fakeroot/compile := $(curdir)/libtool/compile
 $(curdir)/findutils/compile := $(curdir)/bison/compile
 $(curdir)/firmware-utils/compile += $(curdir)/cmake/compile
 $(curdir)/flex/compile := $(curdir)/libtool/compile
+$(curdir)/genext2fs/compile := $(curdir)/libtool/compile
 $(curdir)/gengetopt/compile := $(curdir)/libtool/compile
 $(curdir)/gmp/compile := $(curdir)/libtool/compile
 $(curdir)/isl/compile := $(curdir)/gmp/compile