nptl: Consolidate sem_open implementations

Current sparc32 sem_open and default one only differ on:

  1. Default one contains a 'futex_supports_pshared' check.
  2. sem.newsem.pad is initialized to zero.

This patch removes sparc32 and sparc32v9 sem_open arch specific
implementation and instead set sparc32 to use nptl default one.
Using 1. is fine since it should always evaluate 0 for Linux
(an optimized away by the compiler). Adding 2. to default
implementation should be ok since 'pad' field is used mainly
on sparc32 code.

I checked on i686 and checked a sparc32v9 build.

	* nptl/sem_open.c (sem_open): Init pad value to 0.
	* sysdeps/sparc/sparc32/sem_open.c: Remove file.
	* sysdeps/sparc/sparc32/sparcv9/sem_open.c: Likewise.