DWARF: Emit address of __gshared variable correctly on I64
fix Issue 12956 - [ICE] Assertion in expression.c:432
Merge pull request #3684 from 9rnsr/fix12956

[REG2.065] Issue 12956 - [ICE] Assertion in expression.c:432
Merge pull request #3681 from ibuclaw/dwopaddr

DWARF: Emit address of __gshared variable correctly on I64