[ARM,PowerPC] shouldForceRelocation: check MCValue::Specifier
Follow-up to 38c3ad36be1facbe6db2dede7e93c0f12fb4e1dc
Removes reliance on a MCAssembler::evaluateFixup hack
`if (Target.SymSpecifier || SA.isUndefined()) {` (previosuly
`if (A->getKind() != MCSymbolRefExpr::VK_None || SA.isUndefined()) {`)
Target.SymSpecifier will soon go away when MCValue replaces
MCSymbolRefExpr members with MCSymbol and removes the temporary
`SymSpecifier` workaround.