The assertion added via 264b188 (Using atomic counters on shared
containers (RoaringBitmap#473), 2023-05-15) does not explicitly include <assert.h>
causing GCC to fail compilation when invoked with
`-Werror=implicit-function-declaration`.

In C++ this is OK, since there `assert()` refers to its macro
definition. But in C the only way to get `assert()` is by including
<assert.h>.

Signed-off-by: Taylor Blau <[email protected]>

* portability.h: include missing `<assert.h>`

The assertion added via 264b188 (Using atomic counters on shared
containers (#473), 2023-05-15) does not explicitly include <assert.h>
causing GCC to fail compilation when invoked with
`-Werror=implicit-function-declaration`.

In C++ this is OK, since there `assert()` refers to its macro
definition. But in C the only way to get `assert()` is by including
<assert.h>.

Signed-off-by: Taylor Blau <[email protected]>

* src: avoid old-style function declarations

A handful of functions with argument arity zero fail when the compiler
is invoked with `-Werror=old-style-definition`. Work around these by
explicitly declaring the parameter list as `void` to clarify that these
functions expect zero arguments.

Signed-off-by: Taylor Blau <[email protected]>

* roaring_array.h: declare `ra_get_container()`

This function dates all the way back to 3d12719 (some more untested
code, plus some files that had not been tracked hitherto, 2016-01-19),
but never had a prototype.

This causes compilers building with `-Werror=missing-prototypes` to fail
compilation. Declare a prototype for that function in the corresponding
header accordingly.

Signed-off-by: Taylor Blau <[email protected]>

* containers/bitset.h: declare `bitset_container_union_nocard()`

In a similar spirit as the previous commit, declare a function prototype
for `bitset_container_union_nocard()` which rounds out the existing set
of function prototypes for the macro expansion of:

    BITSET_CONTAINER_FN(union, |, _mm256_or_si256, vorrq_u64)

Signed-off-by: Taylor Blau <[email protected]>

* containers/bitset.h: declare `bitset_container_intersection_nocard()`

In a similar spirit as the previous commits, declare a function
prototype for `bitset_container_intersection_nocard()` which rounds out
the existing set of function prototypes for the macro expansion of:

    BITSET_CONTAINER_FN(intersection, &, _mm256_and_si256, vandq_u64)

Signed-off-by: Taylor Blau <[email protected]>

---------

Signed-off-by: Taylor Blau <[email protected]>