treewide: fix some strict-prototypes Clang warnings/errors

Clang 15 at least with my build configuration emits warnings about
function prototypes that lack argument types. Most notably this
happens with functions that take no arguments which in compiler view
equates to the void type i.e. void f(void) instead of void f(). As I
understand, this will become an error in some future Clang release,
so might as well fix it now.

Since these were discovered not by a linter but by the actual compiler
for my particular build configuration, some f() may have escaped for
now. But at least it's enough to build PipeWire with most optional
features enabled even when -Werror=strict-prototypes is enabled.

For anyone else wanting to have a go at this, these can be upgraded
from warnings to errors by adding -Werror=strict-prototypes to the
custom CFLAGS which probably works with GCC, too, but has only been
done with Clang 15.0.2.

Finally my editor automatically stripped trailing spaces upon saving
the modified files. I assume it's probably not worth keeping those
invisible bytes around but this may have slightly dubious implications
as it did also turn indented empty lines of JACK license header into
regular empty lines.

Signed-off-by: Niklāvs Koļesņikovs <89q1r14hd@relay.firefox.com>

pipewire-jack/src/pipewire-jack.c

@@ -5715,7 +5715,7 @@ jack_nframes_t jack_time_to_frames(const jack_client_t *client, jack_time_t usec
 }
 
 SPA_EXPORT
-jack_time_t jack_get_time()
+jack_time_t jack_get_time(void)
 {
 	struct timespec ts;
 	clock_gettime(CLOCK_MONOTONIC, &ts);

pipewire-jack/src/uuid.c

@@ -33,7 +33,7 @@
 #include <pipewire/pipewire.h>
 
 SPA_EXPORT
-jack_uuid_t jack_client_uuid_generate ()
+jack_uuid_t jack_client_uuid_generate (void)
 {
 	static uint32_t uuid_cnt = 0;
 	jack_uuid_t uuid = 0x2; /* JackUUIDClient */;