Object, ELF: Use error code instead of calling report_fatal_error()

Make createELFObjectFile() return object_error::parse_failed on
encountering invalid ELF file, instead of crashing the program.

llvm-svn: 238481
diff --git a/llvm/test/DebugInfo/dwarfdump-invalid.test b/llvm/test/DebugInfo/dwarfdump-invalid.test
new file mode 100644
index 0000000..db77e4e
--- /dev/null
+++ b/llvm/test/DebugInfo/dwarfdump-invalid.test
@@ -0,0 +1,4 @@
+; Verify that llvm-dwarfdump doesn't crash on broken input files.
+
+RUN: llvm-dwarfdump %p/Inputs/invalid.elf
+