configure: corrected issue in Makefile.am and removed noinst build of umax_pp tool

Currently, there is no way to disable the build of the umax_pp low level sources because the tool umax_pp is always built. Some platforms cannot build the umax_pp low level code so this causes problems.

Disabling the umax_pp backend is not sufficient because the tool is built regardless. Disabling the build of the backend merely affects whether umax_pp tool is installed or not.

I have removed the noinst option to build but not install this program. This tool is not required for the build so we need not build it if we are not installing it.