Merging r198744:

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r198744 | iain | 2014-01-08 05:22:54 -0500 (Wed, 08 Jan 2014) | 8 lines

[patch] Adjust behavior of FDE cross-section relocs for targets that don't support abs-differences.

Modern versions of OSX/Darwin's ld (ld64 > 97.17) have an optimisation present that allows the back end to omit relocations (and replace them with an absolute difference) for FDE some text section refs.

This patch allows a backend to opt-in to this behaviour by setting "DwarfFDESymbolsUseAbsDiff".  At present, this is only enabled for modern x86 OSX ports.

test changes by David Fang.

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llvm-svn: 205768