Consolidate Linux select implementation

Consolidate Linux select implementation

This patch consolidates the select Linux syscall implementation on
sysdeps/unix/sysv/linux/select.c.  The changes are:

  1. Remove select from auto-generation syscalls.list on the architecture
     that uses __NR_select.
  2. Remove generic implementation add a default one that handle all
     current cases (with the expection of alpha)
     The new default implementation will either use __NR_select if
     available of fallback to __NR_pselect6 otherwise.
  3. Add a alpha outlier implementation which requires old compatibility
     symbols.

Checked on i686-linux-gnu, x86_64-linux-gnu, x86_64-linux-gnux32,
arch64-linux-gnu, arm-linux-gnueabihf, and powerpc64le-linux-gnu.

	* sysdeps/unix/sysv/linux/alpha/Makefile (sysdep_routines): Add
	osf_select.
	* sysdeps/unix/sysv/linux/alpha/select.c: New file.
	* sysdeps/unix/sysv/linux/alpha/syscalls.list: Remove select and
	osf_select from auto-generation list.
	* sysdeps/unix/sysv/linux/syscalls.list: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/syscalls.list: Likewise.
	* sysdeps/unix/sysv/linux/generic/select.c: Remove file.
	* sysdeps/unix/sysv/linux/select.c: New file.