Add comment with symtab_command decl to clarify reads

Author: jasonmolenda

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

@@ -2276,6 +2276,14 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
     // Watch for the symbol table load command
     switch (lc.cmd) {
     case LC_SYMTAB:
+      // struct symtab_command {
+      //   uint32_t        cmd;            /* LC_SYMTAB */
+      //   uint32_t        cmdsize;        /* sizeof(struct symtab_command) */
+      //   uint32_t        symoff;         /* symbol table offset */
+      //   uint32_t        nsyms;          /* number of symbol table entries */
+      //   uint32_t        stroff;         /* string table offset */
+      //   uint32_t        strsize;        /* string table size in bytes */
+      // };
       symtab_load_command.cmd = lc.cmd;
       symtab_load_command.cmdsize = lc.cmdsize;
       symtab_load_command.symoff = m_data.GetU32(&offset);