Miscellaneous fixes for Tier 2

[pfez]

This commit removes old obsolete decompilation tests, that were no longer used, and replaces them with tests for various features of the decompiler.

• DLA capability to recover complex data structure like linked-lists and arrays.
• DLA capability to update segment and section types, so that we emit nice looking accesses to segments in C.
• Capability to emit nice looking integer literals in C
• Capability to emit inline string literals in C and update the model types of the segments containg such string literals.

All the actual tests are implmented in revng-c, based on FileCheck. Here we're adding only the original source, and recipes to compile the code to generated the binaries that are then used in revng-c for tests.

[pfez]

This is the updated version of https://github.com/revng/revng-qa/pull/22

I already integrated all the comments that were opened there