GNU Make 3.81 compatibility

3.81 doesn't understand the ‘define foo =’ syntax, which was added in
3.82.  So use ‘define foo’ instead.
Create the target directory of libraries and programs
Remove dead code
Support DESTDIR
Merge commit 'a210c995cdd9279ed4137ec5d2e4cc928cb36097'
Install header files
Fix the RPM build