Breakpad Linux dumper: Handle STABS-in-symbol-table, and line number records outside functions.

This patch addresses two differences between Linux and Macintosh OS X STABS
data:

- StabsReader assumes that the STABS entries follow the conventions for
  storing STABS data in object file sections (that is, .stabs and
  .stabstr), rather than in the object files's linker symbol table. On Mac
  OS X, STABS entries live in the Mach-O file's LC_SYMTAB load command,
  along with all the other linker symbols; they are not grouped into units
  by N_UNDF entries.

  This patch adds a boolean argument to the StabsReader constructor
  indicating whether the parser should treat N_UNDF entries as unit
  boundaries; this argument should be true on Linux, and false on Mac. The
  patch changes src/common/linux/dump_symbols.cc to pass this new argument.

- Mac OS X STABS place SLINE (line number) records immediately before the
  FUN record for the function to which they belong, and the values of such
  records are absolute, not relative to the function start.

  This patch extends the parser to queue up such records and report them to
  the handler when we do see the FUN record. The meaning of
  StabsHandler::Line remains unchanged; existing handlers do not need to be
  adjusted.

This patch also adds unit tests for the new parser behaviors.

a=jimblandy, r=mark


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@587 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/linux/dump_symbols.cc

@@ -142,12 +142,13 @@ static bool LoadStabs(const ElfW(Ehdr) *elf_header,
   StabsToModule handler(module);
   // Find the addresses of the STABS data, and create a STABS reader object.
   // On Linux, STABS entries always have 32-bit values, regardless of the
-  // address size of the architecture whose code they're describing.
+  // address size of the architecture whose code they're describing, and
+  // the strings are always "unitized".
   uint8_t *stabs = reinterpret_cast<uint8_t *>(stab_section->sh_offset);
   uint8_t *stabstr = reinterpret_cast<uint8_t *>(stabstr_section->sh_offset);
   google_breakpad::StabsReader reader(stabs, stab_section->sh_size,
                                       stabstr, stabstr_section->sh_size,
-                                      big_endian, 4, &handler);
+                                      big_endian, 4, true, &handler);
   // Read the STABS data, and do post-processing.
   if (!reader.Process())
     return false;