cbfstool: add symbol table parsing to the ELF parser

Optionally parse the symbol table contained within an ELF
file. It currently assumes there is only one symbol table present,
and it errors out if more than one is found.

Change-Id: I4ac4ad03184a319562576d8ab24fa620e701672a
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5376
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>

util/cbfstool/elfparsing.h

@@ -41,12 +41,15 @@ struct parsed_elf {
 	 * entry.
 	 */
 	struct buffer **strtabs;
+	/* Parsed symbols. */
+	Elf64_Sym *syms;
 };
 
 #define ELF_PARSE_PHDR		(1 << 0)
 #define ELF_PARSE_SHDR		(1 << 1)
 #define ELF_PARSE_RELOC		(1 << 2)
 #define ELF_PARSE_STRTAB	(1 << 3)
+#define ELF_PARSE_SYMTAB	(1 << 4)
 
 #define ELF_PARSE_ALL		(-1)