package/android-tools: add option to build ext4 utils for the host

package/android-tools: add option to build ext4 utils for the host

This patch adds an option to build and install the ext4_utils for the
host, i.e. make_ext4fs, ext4fixup, ext2simg, img2simg, simg2img and
simg2simg.

Signed-off-by: Alex Kaplan <kaplan2539@gmail.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas:
 - simplify a bit the installation logic by using a single
   HOST_ANDROID_TOOLS_INSTALL_TARGETS variable, instead of having one
   specific for ext4 tools
 - drop "default n" from Config.in.host]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>