new altera unroll loops check

This lint check is a part of the FLOCL (FPGA Linters for OpenCL)
project out of the Synergy Lab at Virginia Tech.

FLOCL is a set of lint checks aimed at FPGA developers who write code
in OpenCL.

The altera unroll loops check finds inner loops that have not been
unrolled, as well as fully-unrolled loops that should be partially
unrolled due to unknown loop bounds or a large number of loop
iterations.

Based on the Altera SDK for OpenCL: Best Practices Guide.