[ARM] Fix ld.so crash when built using Binutils 2.29

[ARM] Fix ld.so crash when built using Binutils 2.29

There is bug report that ld.so in GLIBC 2.24 built by Binutils 2.29 will crash
on arm-linux-gnueabihf.  This is confirmed, and the details is at:

   https://sourceware.org/bugzilla/show_bug.cgi?id=21725.

As analyzed in the PR, the old code was with the assumption that assembler
won't set bit0 of thumb function address if it comes from PC-relative
instructions and the calculation can be finished during assembling.  This
assumption however does not hold after PR gas/21458.

	* sysdeps/arm/dl-machine.h (elf_machine_load_address):  Also strip bit 0
	of pcrel_address under Thumb mode.