AArch64: implement first relocation required for MCJIT

R_AARCH64_PCREL32 is present in even trivial .eh_frame sections and so
is required to compile any function without the "nounwind" attribute.

This change implements very basic infrastructure in the RuntimeDyldELF
file and allows (for example) the test-shift.ll MCJIT test to pass
on AArch64.

llvm-svn: 181131
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
index 12e3122..2382544 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h
@@ -49,6 +49,12 @@
                             uint32_t Type,
                             int32_t Addend);
 
+  void resolveAArch64Relocation(const SectionEntry &Section,
+                                uint64_t Offset,
+                                uint64_t Value,
+                                uint32_t Type,
+                                int64_t Addend);
+
   void resolveARMRelocation(const SectionEntry &Section,
                             uint64_t Offset,
                             uint32_t Value,