Add missing void argument, and include include pa_jack.h in pa_jack.c (#347)

* Update pa_jack.c

include `pa_jack.h` in `pa_jack.c`, which provides prototypes for PaJack_SetClientName() and PaJack_GetClientName()

* Update pa_unix_util.h

PaUnixThreading_Initialize() is not a prototype in C, make it PaUnixThreading_Initialize(void)

* Update pa_unix_util.c

make PaUnixThreading_Initialize definition correspond to prototype

src/hostapi/jack/pa_jack.c

@@ -71,6 +71,8 @@
 #include "pa_ringbuffer.h"
 #include "pa_debugprint.h"
 
+#include "pa_jack.h"
+
 static pthread_t mainThread_;
 static char *jackErr_ = NULL;
 static const char* clientName_ = "PortAudio";

src/os/unix/pa_unix_util.c

@@ -236,7 +236,7 @@ pthread_t paUnixMainThread = 0;
 pthread_t paUnixMainThread = 0;
 #endif
 
-PaError PaUnixThreading_Initialize()
+PaError PaUnixThreading_Initialize( void )
 {
     paUnixMainThread = pthread_self();
     return paNoError;

src/os/unix/pa_unix_util.h

@@ -157,7 +157,7 @@ typedef struct
 
 /** Initialize global threading state.
  */
-PaError PaUnixThreading_Initialize();
+PaError PaUnixThreading_Initialize( void );
 
 /** Perish, passing on eventual error code.
  *