Modify GCC build system to install `caf` and `cafrun` scripts

[rouson]

Request for Enhancement (RFE)

Once the modified GCC build system is capable of installing the caf_mpi library, the build system should be adapted to install a caf compiler wrapper and cafrun program launcher similar to the like-named scripts that the OpenCoarrays CMake build system installs.

[dcelisgarza]

After merging with #20 and downloading the prerequisites, both autoconf and the subsequently generated configure script work with the new configure.ac that conditionally checks for mpich when fortran is to be built.

However make fails at building g++ with the following error.

g++: error: gengtype-lex.c: No such file or directory
g++: fatal error: no input files
compilation terminated.

I've been googling and have come up with nothing.

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Edit:

1. Just now i find out about flex, I'm trying again.
2. Ok so far so good, the thing keeps failing at make but it's not my additions that make it so.
3. I'm disabling bootstrap to see what happens.