fast-builder/libplsdk/Makefile: add libplhw.a

The Plastic Logic hardware user-side library libplhw is
now part of the PLSDK package, so it's added to the
libplsdk.so shared library.
fast-builder/Makefile: add libplhw and plhwtools
gitignore: add Makefile (that's for libplsdk.so)

The libplsdk.so Makefile is copied to the top-level
of the plsdk directory by repo as part of the fast-builder
source tree set-up.  It is already under source control
in fast-builder/libplsdk/Makefile so it should be ignored
here.
android-ndk/Application.mk: add plhwtools
doxygen/Doxyfile: add libplhw.h to the list of input files