Enable minimized symbol tables when parsing mach-o files. This

new change will omit unneeded symbol table entries and coalesce
function entries (N_FUN stab entries) with their linker code
symbol (N_SECT symbols) into only the function symbol to avoid
duplicate symbol table entries. It will also coalesce N_STSYM and
the data linker symbol into just one static data symbol.

llvm-svn: 113363