Build system:
* Honour DESTDIR, avoiding need for prefix= workaround.
[Contribution from Sergey Poznyakoff]
- * regression tests: Add missing dependency on hsyscalls.i.
+ * regression tests: Add missing dependency on hsyscalls.h.
GNU #51329. [Report from Sergei Trofimovich]
* regression tests: build with 64-bit time_t on 32-bit systems.
Debian #1065725, Ubuntu Launchpad #2057735.