Most code in newlib already uses unified syntax, but just a couple of
laggards remain. This patch removes these and means the the entire
code base has now been converted.
* arm/Makefile.in: Add Linux syscall interface.
* arm/linux-crt0.S: New file.
* arm/linux-syscall.h: New file.
* arm/linux-syscalls0.S: New file.
* arm/linux-syscalls1.c: New file.