ld: Don't define __rel[a]_iplt_start/__rel[a]_iplt_end in PIE
__rel[a]_iplt_start and __rel[a]_iplt_end are defined to handle IFUNC in
static executables. For PIE, since IFUNC is handled as the part of the
normal dynamic relocation processing, there is no need to define these
symbols in PIE.
* scripttempl/elf.sc (CREATE_PIC): New. Set for CREATE_SHLIB or
CREATE_PIE.
(__rel_iplt_start): Don't define for CREATE_PIC.
(__rel_iplt_end): Likewise.
(__rela_iplt_start): Likewise.
(__rela_iplt_end): Likewise.