checkpath: fix allocation size of path buffer

strlen's return value isn't enough to be used
directly for (x)malloc; it doesn't include
the null byte at the end of the string.

X-Gentoo-Bug: 816900
X-Gentoo-Bug-URL: https://bugs.gentoo.org/816900
Fixes: #459
Fixes: #462

src/rc/checkpath.c

@@ -151,7 +151,7 @@ static char *clean_path(char *path)
 	char *ch;
 	char *ch2;
 	char *str;
-	str = xmalloc(strlen(path));
+	str = xmalloc(strlen(path) + 1);
 	ch = path;
 	ch2 = str;
 	while (true) {