Remove some useless typedef's.

[sas]

Summary

This does not have any functionnal difference but I found myself
searching for 'struct RegisterInfo$' to find a definition and couldn't
find it. The version without typedef seems more common so let's try and
be consistent.

include/lldb/lldb-private-types.h

namespace lldb_private
     typedef llvm::sys::DynamicLibrary (*LoadPluginCallbackType)(const lldb::DebuggerSP &debugger_sp,
                                                                 const FileSpec &spec, Error &error);
 
     //----------------------------------------------------------------------
     // Every register is described in detail including its name, alternate
     // name (optional), encoding, size in bytes and the default display
     // format.
     //----------------------------------------------------------------------
-    typedef struct
+    struct RegisterInfo
     {
         const char *name;        // Name of this register, can't be NULL
         const char *alt_name;    // Alternate name of this register, can be NULL
         uint32_t byte_size;      // Size in bytes of the register
         uint32_t byte_offset;    // The byte offset in the register context data where this register's value is found.
                                  // This is optional, and can be 0 if a particular RegisterContext does not need to
                                  // address its registers by byte offset.
         lldb::Encoding encoding; // Encoding of the register bits
         lldb::Format format;     // Default display format
         uint32_t kinds[lldb::kNumRegisterKinds]; // Holds all of the various register numbers for all register kinds
         uint32_t *value_regs;      // List of registers (terminated with LLDB_INVALID_REGNUM).  If this value is not
                                    // null, all registers in this list will be read first, at which point the value 
                                    // for this register will be valid.  For example, the value list for ah
                                    // would be eax (x86) or rax (x64).
         uint32_t *invalidate_regs; // List of registers (terminated with LLDB_INVALID_REGNUM).  If this value is not
                                    // null, all registers in this list will be invalidated when the value of this
                                    // register changes.  For example, the invalidate list for eax would be rax
                                    // ax, ah, and al.
-    } RegisterInfo;
+    };
 
     //----------------------------------------------------------------------
     // Registers are grouped into register sets
     //----------------------------------------------------------------------
-    typedef struct
+    struct RegisterSet
     {
         const char *name;           // Name of this register set
         const char *short_name;     // A short name for this register set
         size_t num_registers;       // The number of registers in REGISTERS array below
         const uint32_t *registers;  // An array of register indices in this set.  The values in this array are
                                     // *indices* (not register numbers) into a particular RegisterContext's
                                     // register array.  For example, if eax is defined at index 4 for a
                                     // particular RegisterContext, eax would be included in this RegisterSet
                                     // by adding the value 4.  Not by adding the value lldb_eax_i386.
-    } RegisterSet;
+    };
 
-    typedef struct
+    struct OptionEnumValueElement
     {
         int64_t value;
         const char *string_value;
         const char *usage;
-    } OptionEnumValueElement;
+    };
 
     struct OptionValidator
     {
         virtual ~OptionValidator() { }
         virtual bool IsValid(Platform &platform, const ExecutionContext &target) const = 0;
         virtual const char * ShortConditionString() const = 0;
         virtual const char * LongConditionString() const = 0;
     };
-    
     struct OptionDefinition
     {
         uint32_t usage_mask;                     // Used to mark options that can be used together.  If (1 << n & usage_mask) != 0
                                                  // then this option belongs to option set n.
         bool required;                           // This option is required (in the current usage level)
         const char *long_option;                 // Full name for this option.
         int short_option;                        // Single character for this option.
         int option_has_arg;                      // no_argument, required_argument or optional_argument