Fix PR18841 ifunc relocation ordering

In order to get the ifunc relocs properly sorted the correct class
needs to be returned.  The code mimics what has been done for AArch64.

Fixes:
FAIL: Run pr18841 with libpr18841b.so
FAIL: Run pr18841 with libpr18841c.so
FAIL: Run pr18841 with libpr18841bn.so (-z now)
FAIL: Run pr18841 with libpr18841cn.so (-z now)

	bfd/
	PR ld/18841
	* elf32-arm.c (elf32_arm_reloc_type_class): Return
	reloc_class_ifunc for ifunc symbols.

	ld/testsuite/
	* ld-arm/ifunc-12.rd: Update relocations order.
	* ld-arm/ifunc-3.rd: Likewise.
	* ld-arm/ifunc-4.rd: Likewise.