Make shadow_logfd and Prog not extern

Closes #444
Closes #465

Signed-off-by: Serge Hallyn <serge@hallyn.com>

lib/shadowlog.c

@@ -0,0 +1,28 @@
+#include "shadowlog.h"
+
+#include "lib/shadowlog_internal.h"
+
+void log_set_progname(const char *progname)
+{
+	Prog = progname;
+}
+
+const char *log_get_progname(void)
+{
+	return Prog;
+}
+
+void log_set_logfd(FILE *fd)
+{
+	if (NULL != fd)
+		shadow_logfd = fd;
+	else
+		shadow_logfd = stderr;
+}
+
+FILE *log_get_logfd(void)
+{
+	if (shadow_logfd != NULL)
+		return shadow_logfd;
+	return stderr;
+}