Possible fix for mingw Win32 dll linking of nanosleep

include/hamlib/rig.h

@@ -2439,6 +2439,7 @@ extern HAMLIB_EXPORT(const char *) rig_copyright HAMLIB_PARAMS(());
 HAMLIB_EXPORT(void) rig_no_restore_ai();
 
 #include <unistd.h>
+#include <pthread.h> // so configure can pick up nanosleep on Win32
 extern HAMLIB_EXPORT(int) hl_usleep(useconds_t msec);
 
 __END_DECLS

src/sleep.c

@@ -38,6 +38,12 @@
 #include <unistd.h>
 #include <errno.h>
 #include <time.h>
+#include <pthread.h>
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
 
 // In order to stop the usleep warnings in cppcheck we provide our own interface
 // So this will use system usleep or our usleep depending on availability of nanosleep
@@ -91,3 +97,7 @@ int usleep(useconds_t usec)
     return 0;
 }
 #endif // HAVE_NANOSLEEP
+
+#ifdef __cplusplus
+}
+#endif