MC/ELF: Allow targets to set ABI version

Tests are in the follow up change

Differential Revision: https://reviews.llvm.org/D57810

llvm-svn: 354072
diff --git a/llvm/lib/MC/MCELFObjectTargetWriter.cpp b/llvm/lib/MC/MCELFObjectTargetWriter.cpp
index 9ad7f8c..a81eab9 100644
--- a/llvm/lib/MC/MCELFObjectTargetWriter.cpp
+++ b/llvm/lib/MC/MCELFObjectTargetWriter.cpp
@@ -12,8 +12,9 @@
 
 MCELFObjectTargetWriter::MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_,
                                                  uint16_t EMachine_,
-                                                 bool HasRelocationAddend_)
-    : OSABI(OSABI_), EMachine(EMachine_),
+                                                 bool HasRelocationAddend_,
+                                                 uint8_t ABIVersion_)
+    : OSABI(OSABI_), ABIVersion(ABIVersion_), EMachine(EMachine_),
       HasRelocationAddend(HasRelocationAddend_), Is64Bit(Is64Bit_) {}
 
 bool MCELFObjectTargetWriter::needsRelocateWithSymbol(const MCSymbol &Sym,