Makefile.classic: use DESTDIR at install targets
Makefile.classic: use DESTDIR at install targets

this is a standard method to allow using the directory location within
build, so that the DESTDIR will not be considered.

it also allows packager to specify LIBDIR for example, without the
DESTDIR component.

Signed-off-by: Alon Bar-Lev <bb308b7fcc6eb1364576b94f9dfcd9006c6c579d@gmail.com>

Nmishin/tc-play,veracrypt/tc-play,bwalex/tc-play,Nmishin/tc-play,veracrypt/tc-play,Nmishin/tc-play,bwalex/tc-play,veracrypt/tc-play,bwalex/tc-play