ld/ARM: Fix IFUNC and TLS descriptors in the same shared object

ld/ARM: Fix IFUNC and TLS descriptors in the same shared object

Combining TLS descriptors and GNU indirect functions in the same
object could lead to assertions or multiple dynamic relocations
for the same GOT slot. Fix the bookkeeping so this doesn't happen.

This allows building and make checking glibc with -mtls-dialect=gnu2.

bfd/ChangeLog:

2014-06-16  Will Newton  <will.newton@linaro.org>

	* elf32-arm.c (elf32_arm_allocate_plt_entry): Increment
	htab->next_tls_desc_index in the non-IPLT case.
	Calculate GOT offset correctly for the non-IPLT case.
	(allocate_dynrelocs_for_symbol): Don't increment
	htab->next_tls_desc_index here.

ld/testsuite/ChangeLog:

2014-06-16  Will Newton  <will.newton@linaro.org>

	* ld-arm/arm-elf.exp: Add ifunc-gdesc test.
	* ld-arm/ifunc-gdesc.r: New file.
	* ld-arm/ifunc-gdesc.s: Likewise.
	* ld-arm/ifunc-gdesc.ver: Likewise.