Fix parsing of hexadecimal float constants

Thanks to Chucky Ellison.
Argument promotions in calls to variadic functions

Thanks to Chucky Ellison and Elnatan Reisner.
Remove -cclib (breaks build on 3.12)
Remove -cclib in comments (breaks build on 3.12)
Print #line before goto statements

Thanks to Elnatan Reisner.
FLEXLINK flag to handle OCaml >= 3.11 on Windows
Enable flexlink trick and run configure
Remove one more occurrence of -cclib
Fix configure script for FLEXLINK
Fix switch default ordering bug

Thanks to Elnatan Reisner.
Remove case after a default (in switch)

Thanks to Elnatan Reisner.
Fix default parsing (in switch)

Thanks to Elnatan Reisner.
Add regtest for default parsing
Simpler switch names

Thanks to Elnatan Reisner.
Use || when simplifying switches

Based on an idea by Elnatan Reisner.
Do not indent else-if

Thanks to Elnatan Reisner.
Fix evaluation order in Util.list_map

This fixes three regression tests (about variable-sized arrays) in
CIL.  Thanks to Foivos Zakkak for the bug report.
Fix #3133015: displays wrong hexadcimal constants

Removed legacy code: constant-folding shall not produce negative
integers for unsigned variables anymore (except for 64-bits ones).
Test variable-length multidimensional arrays
Remove if statements with no side-effect

This avoids some conditional variables, and applies
to ?: too.  Thanks to Elnatan Reisner for the idea.