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/dwarf_cu_to_module.h

@@ -158,6 +158,11 @@ class DwarfCUToModule: public dwarf2reader::RootDIEHandler {
     // covered by no function.
     virtual void UncoveredLine(const Module::Line &line);
 
+    // The DW_TAG_subprogram DIE at OFFSET has no name specified directly
+    // in the DIE, nor via a DW_AT_specification or DW_AT_abstract_origin
+    // link.
+    virtual void UnnamedFunction(uint64 offset);
+
    protected:
     string filename_;
     uint64 cu_offset_;