Google Breakpad Issue 417: Handle DWARF that omits function names.

This patch makes sure dump_syms behaves properly when presented with
malformed DWARF data that provides no name for a function. We print a
warning message to stderr, and subsitute "<name omitted>" for the empty
string, so that the "FUNC" record written to the symbol file for the
function is still well-formed. (We may have line number data covering the
function, so it would be a shame to omit the function altogether.)

Unit tests included.
a=jimblandy, r=ted.mielczarek


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@779 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/module.cc

@@ -33,6 +33,7 @@
 
 #include "common/module.h"
 
+#include <assert.h>
 #include <errno.h>
 #include <string.h>
 
@@ -65,6 +66,9 @@ void Module::SetLoadAddress(Address address) {
 }
 
 void Module::AddFunction(Function *function) {
+  // FUNC lines must not hold an empty name, so catch the problem early if
+  // callers try to add one.
+  assert(!function->name.empty());
   std::pair<FunctionSet::iterator,bool> ret = functions_.insert(function);
   if (!ret.second) {
     // Free the duplicate that was not inserted because this Module