interval.h: add missing header
The ssize_t type requires the unistd.h header. This fixes build with musl
libc:
In file included from ../include/tinyalsa/limits.h:32:0,
from limits.c:1:
../include/tinyalsa/interval.h:38:2: error: unknown type name 'ssize_t'
ssize_t max;
^
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
diff --git a/include/tinyalsa/interval.h b/include/tinyalsa/interval.h
index 3f6f3dc..068571d 100644
--- a/include/tinyalsa/interval.h
+++ b/include/tinyalsa/interval.h
@@ -30,6 +30,7 @@
#define TINYALSA_INTERVAL_H
#include <stdlib.h>
+#include <unistd.h>
/** A closed range signed interval. */