m32r: switch to generic sys_execve()

... and get rid of the horrors in fork()/vfork()/clone() prototypes.
It's fscking faster to calculate pt_regs in question than to fetch
the pointer from stack...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/m32r/include/asm/ptrace.h

@@ -139,6 +139,8 @@ extern void withdraw_debug_trap(struct pt_regs *regs);
 
 #define task_pt_regs(task) \
         ((struct pt_regs *)(task_stack_page(task) + THREAD_SIZE) - 1)
+#define current_pt_regs() ((struct pt_regs *) \
+	((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
 
 #endif /* __KERNEL */
 

arch/m32r/include/asm/unistd.h

@@ -352,6 +352,7 @@
 #define __ARCH_WANT_SYS_OLDUMOUNT
 #define __ARCH_WANT_SYS_RT_SIGACTION
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
+#define __ARCH_WANT_SYS_EXECVE
 
 #define __IGNORE_lchown
 #define __IGNORE_setuid