V6 [PATCH] x86: Only allow S - A relocations against absolute symbol

[Alan Modra]

Seen here on Ubuntu 18.04 when using a number of different gcc
versions.

FAIL: Run pr25749-1bb (-no-pie -fno-PIE)
FAIL: Run pr25749-1bb (-pie -fPIE)
FAIL: Run pr25749-2ab (-no-pie -fno-PIE)
FAIL: Run pr25749-2ab (-pie -fPIE)

-- 
Alan Modra
Australia Development Lab, IBM