Add various tests for decompilation

[pfez]

This patchset adds 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

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]

Ok I'll take the reviews, and move this to revng-c. Thanks for the feedback. Closing the MR here then.