building-process: simplified the process of making installation directory

In install target, foo and $(DESTDIR)foo are made for each foo.
However, making $(DESTDIR)foo is enough. Suppress the lines maing
foo.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
renamed Data dir to data

I guess upper case characters in a file/directory name are not firendly for windows platform.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
tg: supress all warning reported when make -f maintainer.mak

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
provide the way to run a specific unit test

With UNIT=foo variable foo.d or foo.b can be
run as a test case.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
suppress the output from read shell-builtin command

In testing.mak read shell built-in command is used.  On bash if a
parameter for read is omitted, REPLY variable is used for the place
where read data is stored. This behavior is different from dash.

read of dash prints something. (I have not inspected the output.)
To avoid the output, give a variable name to read shell built-in
explicitly in this patch.

dash is used widely Debian and its variants.
Even on Fedora you can test this patch with SHELL=/bin/dash.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>