ARM libatomic inline asm uses sel, uadd8, uadd16 instructions
which are only available if __ARM_FEATURE_SIMD32 is defined.
libatomic/
2017-01-30 Szabolcs Nagy <szabolcs.nagy@arm.com>
PR target/78945
* config/arm/exch_n.c (libat_exchange): Check __ARM_FEATURE_SIMD32.
From-SVN: r245023
