xorriso: fix musl build

Add a patch that adds the missing header for ssize_t.

Fixes:
http://autobuild.buildroot.net/results/820/82014874f5b97de8504d8409b286889b582a7454/

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/xorriso/0001-fix-musl-build.patch

@@ -0,0 +1,20 @@
+Fix musl build
+
+Add missing header needed for ssize_t.
+
+Signed-off-by: Baruch Siach <baruch@tkos.co.il>
+---
+Patch status: posted upstream
+(http://lists.gnu.org/archive/html/bug-xorriso/2016-05/msg00000.html)
+
+diff -Nuar xorriso-1.4.2-orig/libisofs/aaip_0_2.h xorriso-1.4.2/libisofs/aaip_0_2.h
+--- xorriso-1.4.2-orig/libisofs/aaip_0_2.h	2015-11-28 16:41:33.000000000 +0200
++++ xorriso-1.4.2/libisofs/aaip_0_2.h	2016-05-24 11:40:43.874191174 +0300
+@@ -16,6 +16,7 @@
+ #ifndef Aaip_h_is_includeD
+ #define Aaip_h_is_includeD yes
+ 
++#include <unistd.h>
+ 
+ /* --------------------------------- Encoder ---------------------------- */
+