Add some unit tests for Linux WriteSymbolFile

This patch adds synth_elf::{StringTable,SymbolTable,ELF} classes to
produce in-memory ELF files to properly test the Linux symbol dumping
code. It also uses those classes to add some basic tests for
the WriteSymbolFile function.

R=jimb at http://breakpad.appspot.com/277001/show

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@794 4c0a9323-5329-0410-9bdc-e9ce6186880e
diff --git a/Makefile.am b/Makefile.am
index 4595566..23aebec 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -381,8 +381,11 @@
 	src/common/dwarf/dwarf2reader.cc \
 	src/common/dwarf/dwarf2reader_cfi_unittest.cc \
 	src/common/linux/dump_symbols.cc \
+	src/common/linux/dump_symbols_unittest.cc \
 	src/common/linux/elf_symbols_to_module.cc \
 	src/common/linux/elf_symbols_to_module_unittest.cc \
+	src/common/linux/synth_elf.cc \
+	src/common/linux/synth_elf_unittest.cc \
 	src/common/linux/file_id.cc \
 	src/common/linux/file_id_unittest.cc \
 	src/testing/gtest/src/gtest-all.cc \