Simplify the handling of iterators in ObjectFile.

None of the object file formats reported error on iterator increment. In
retrospect, that is not too surprising: no object format stores symbols or
sections in a linked list or other structure that requires chasing pointers.
As a consequence, all error checking can be done on begin() and end().

This reduces the text segment of bin/llvm-readobj in my machine from 521233 to
518526 bytes.

llvm-svn: 200442
diff --git a/llvm/lib/Object/Object.cpp b/llvm/lib/Object/Object.cpp
index e454d8e..399d460 100644
--- a/llvm/lib/Object/Object.cpp
+++ b/llvm/lib/Object/Object.cpp
@@ -84,9 +84,7 @@
 }
 
 void LLVMMoveToNextSection(LLVMSectionIteratorRef SI) {
-  error_code ec;
-  unwrap(SI)->increment(ec);
-  if (ec) report_fatal_error("LLVMMoveToNextSection failed: " + ec.message());
+  ++(*unwrap(SI));
 }
 
 void LLVMMoveToContainingSection(LLVMSectionIteratorRef Sect,
@@ -111,9 +109,7 @@
 }
 
 void LLVMMoveToNextSymbol(LLVMSymbolIteratorRef SI) {
-  error_code ec;
-  unwrap(SI)->increment(ec);
-  if (ec) report_fatal_error("LLVMMoveToNextSymbol failed: " + ec.message());
+  ++(*unwrap(SI));
 }
 
 // SectionRef accessors
@@ -169,10 +165,7 @@
 }
 
 void LLVMMoveToNextRelocation(LLVMRelocationIteratorRef SI) {
-  error_code ec;
-  unwrap(SI)->increment(ec);
-  if (ec) report_fatal_error("LLVMMoveToNextRelocation failed: " +
-                             ec.message());
+  ++(*unwrap(SI));
 }