Improve makefile dependency generation.
Improve makefile dependency generation.

Generate dependency information during compilation. That speeds up the
compilation process and also causes "make clean" to finish in an
instant, alghough previously it would generate the dependency
information first.

Also pass -MP to dependency generation to create phony targets for
header files to work around errors for removed or renamed header files.

ufal/morphodita,ufal/morphodita,ufal/morphodita,ufal/morphodita,ufal/morphodita,ufal/morphodita,ufal/morphodita,ufal/morphodita