These tests have missing specs, so the large amount of warnings is expected.

There are still many missing specifications, but at least parsing should
succeed for strictly POSIX-compliant code.

Frama-C does not yet support _Alignof and _Alignas, but this header helps
parsing code and emitting a proper error message.

The ambiguous regex led to behavioral differences under a musl-based libc,
such as in Frama-C's Docker images. The new regex is longer, but avoids the
issue.

- Info (expr_node)
- IndexPI (PlusPI synonym)

Clang 13 emits warnings related to uninitialized variables:

variable 'r' is used uninitialized whenever 'if'
condition is false [-Wsometimes-uninitialized]

This is due to the fact that the assert(0) macro, when using Frama-C's libc,
is expanded to __FC_assert. Since it is not known by the compiler, it cannot
consider it as "noreturn" when the condition is zero. Note that adding
'__attribute__ ((__noreturn__))' will not work: Frama-C will assume it
never returns, even when the condition is true.
Initializing the 'r' variables with a default value will not change the
actual behavior, and will avoid the warnings.

'Indeterminate' alarms are alarms about uninitialized memory, escaping pointers
and special floating-point values (infinite and NaN).

These alarms are emitted for functions specified by -eva-warn-copy-indeterminate
option, which is @all by default. These alarms can be disabled for some function
by -eva-warn-copy-indeterminate=-f, in which case they are also disabled for
the argument expressions of calls to [f].

However:
- the @all default value did not include functions without definition
  (for which a specification or a builtin is used).
- 'indeterminate' alarms were emitted anyway for the arguments of calls to
  functions without definition, except for builtins.
So no indeterminate alarms were emitted for the argument expressions of calls
to builtins (unless their definitions were included).

This commit fixes this behavior:
the @all default of -eva-warn-copy-indeterminate option include all functions
and special case for functions without definition or builtins are removed.

It still avoids to emit surch alarms on Eva directives such as Frama_C_show_each.

The preconditions generated in place of behaviors leading to NaN or infinite
floating-point values are now named.