i386: Replace PREINIT_FUNCTION@PLT with *%eax in call

Since we have loaded address of PREINIT_FUNCTION into %eax, we can
avoid extra branch to PLT slot.

	* sysdeps/i386/crti.S (_init): Replace PREINIT_FUNCTION@PLT
	with *%eax in call.

Acked-by: Christian Brauner (Ubuntu) <christian@brauner.io>