fstat64: Fix Build warnings with common-generic ABI build

fstat64: Fix Build warnings with common-generic ABI build

  CC libc/sysdeps/linux/common/fstat64.os
In file included from libc/sysdeps/linux/common/fstat64.c:16:
libc/sysdeps/linux/common/xstatconv.h:28: warning: 'struct kernel_stat'
declared inside parameter list
libc/sysdeps/linux/common/xstatconv.h:28: warning: its scope is only
this definition or declaration, which is probably not what you want
libc/sysdeps/linux/common/fstat64.c: In function 'fstat64':
libc/sysdeps/linux/common/fstat64.c:33: warning: passing argument 2 of
'__syscall_fstat64' from incompatible pointer type
libc/sysdeps/linux/common/fstat64.c:18: note: expected 'struct stat *'
but argument is of type 'struct stat64 *'
-------------------------------------------------------------------

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>