arch/tile: Use <asm-generic/syscalls.h>

With this change we now include <asm-generic/syscalls.h> into the "tile"
version of the header.  To take full advantage of the prototypes there,
we also change our naming convention for "struct pt_regs *" syscalls so
that, e.g., _sys_execve() is the "true" syscall entry, which sets the
appropriate register to point to the pt_regs before calling sys_execve().

While doing this I realized I no longer needed the fork and vfork
entry point stubs, since those functions aren't in the generic
syscall ABI, so I removed them as well.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/sys.c

@@ -110,6 +110,15 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 #define sys_sync_file_range sys_sync_file_range2
 #endif
 
+/* Call the trampolines to manage pt_regs where necessary. */
+#define sys_execve _sys_execve
+#define sys_sigaltstack _sys_sigaltstack
+#define sys_rt_sigreturn _sys_rt_sigreturn
+#define sys_clone _sys_clone
+#ifndef __tilegx__
+#define sys_cmpxchg_badaddr _sys_cmpxchg_badaddr
+#endif
+
 /*
  * Note that we can't include <linux/unistd.h> here since the header
  * guard will defeat us; <asm/unistd.h> checks for __SYSCALL as well.