* make.adb, adaint.c, adaint.h, osint.adb, osint.ads, bcheck.adb
	(*_attr): new subprograms.
	(File_Length, File_Time_Stamp, Is_Writable_File): new subprograms
	(Read_Library_Info_From_Full, Full_Library_Info_Name,
	Full_Source_Name): Now benefit from a previous cache of the file
	attributes, to further save on system calls.
	(Smart_Find_File): now also cache the file attributes. This makes the
	package File_Stamp_Hash_Table useless, and it was removed.
	(Compile_Sources): create subprograms for the various steps of the main
	loop, for readibility and to avoid sharing variables between the
	various steps.

From-SVN: r153747