fix unprototyped function #880435 and missing sentinel
https://sourceforge.net/p/ckpass/bugs/2/
--- a/ckpass.h
+++ b/ckpass.h
@@ -56,7 +56,7 @@ void error_dialog(char *s);
 int open_db(kpass_db *db, const char *filename);
 int read_db(kpass_db *db, const char *filename);
 int decrypt_db(kpass_db *db, const char *password);
-void init_windows();
+void init_windows(const kpass_db *db);
 void draw_groups(const kpass_db *, int, int, bool);
 void draw_entries(const kpass_db *, int, int, int, bool, bool);
 void draw_top_bar(const char *);
--- a/ckpass.c
+++ b/ckpass.c
@@ -677,7 +677,7 @@ int pipeout(const char *command, const char *s)
 		close(pipefd[1]); /* Close write end. */
 		dup2(pipefd[0], 0); /* Dup read end to stdin. */
 
-		execl(command, command, 0);
+		execl(command, command, NULL);
 
 		/* I don't really think these are necessary, but just in case. */
 		close(pipefd[0]);