X86_64: Don't use PLT nor GOT in static archives [BZ #20750]

There is no need to use PLT nor GOT in static archives to branch to a
function, regardless whether static archives is compiled with PIC or
not.  When static archives are used to create dynamic executable,
PLT/GOT may be used.  The resulting executable still works correctly.

	[BZ #20750]
	* sysdeps/x86_64/sysdep.h (JUMPTARGET): Check SHARED instead
	of PIC.