[Ada] Optimization of the Lock-free implementation of protected object

[Arnaud Charlet <charlet at adacore dot com>]

The optimization of the expansion of protected procedure for the lock-free
implementation brings the following changes:
- Several renamings in order to match GCC built-in function wordings.
- Expected_Comp declaration moved to the the declarations list of the procedure
- GCC built-in operation__sync_bool_compare_and_swap replaced by
  __sync_val_compare_and_swap.
- Don't use an atomic compare and swap if Expected_Comp = Desired_Comp

Tested on x86_64-pc-linux-gnu, committed on trunk

2012-07-12  Vincent Pucci  <pucci@adacore.com>

	* exp_ch9.adb (Build_Lock_Free_Unprotected_Subprogram_Body):
	Atomic_Load_N replaced by Lock_Free_Read_N. Atomic_Compare_Exchange_N
	replaced by Lock_Free_Try_Write_N.
	Renaming of several local variables. For
	procedure, Expected_Comp declaration moved to the declaration
	list of the procedure.
	* rtsfind.ads: RE_Atomic_Compare_Exchange_8,
	RE_Atomic_Compare_Exchange_16, RE_Atomic_Compare_Exchange_32,
	RE_Atomic_Compare_Exchange_64, RE_Atomic_Load_8,
	RE_Atomic_Load_16, RE_Atomic_Load_32, RE_Atomic_Load_64,
	RE_Atomic_Synchronize, RE_Relaxed removed.  RE_Lock_Free_Read_8,
	RE_Lock_Free_Read_16, RE_Lock_Free_Read_32, RE_Lock_Free_Read_64,
	RE_Lock_Free_Try_Write_8, RE_Lock_Free_Try_Write_16,
	RE_Lock_Free_Try_Write_32, RE_Lock_Free_Try_Write_64 added.
	* s-atopri.adb: New file.
	* s-atopri.ads (Atomic_Compare_Exchange_8): Renaming of
	parameters.  Import primitive __sync_val_compare_and_swap_1.
	(Atomic_Compare_Exchange_16): Renaming of parameters.
	Import primitive __sync_val_compare_and_swap_2.
	(Atomic_Compare_Exchange_32): Renaming of parameters.
	Import primitive __sync_val_compare_and_swap_4.
	(Atomic_Compare_Exchange_64): Renaming of parameters.  Import
	primitive __sync_val_compare_and_swap_8.
	(Atomic_Load_8): Ptr renames parameter X.
	(Atomic_Load_16): Ptr renames parameter X.
	(Atomic_Load_32): Ptr renames parameter X.
	(Atomic_Load_64): Ptr renames parameter X.
	(Lock_Free_Read_8): New routine.
	(Lock_Free_Read_16): New routine.
	(Lock_Free_Read_32): New routine.
	(Lock_Free_Read_64): New routine.
	(Lock_Free_Try_Write_8): New routine.
	(Lock_Free_Try_Write_16): New routine.
	(Lock_Free_Try_Write_32): New routine.
	(Lock_Free_Try_Write_64): New routine.

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