* atree.ads, einfo-utils.ads, einfo-utils.adb, fe.h, gen_il.adb,
gen_il.ads, gen_il-gen-gen_entities.adb,
gen_il-gen-gen_nodes.adb, sem_ch12.adb, sem_ch3.adb,
sem_util.adb, sinfo-utils.ads, treepr.adb, types.ads: Clean up
??? comments and other comments.
* atree.adb: Clean up ??? comments and other comments.
(Validate_Node): Fix bug: "Off_0 (N) < Off_L (N)"
should be "Off_0 (N) <= Off_L (N)".
* gen_il-gen.adb, gen_il-gen.ads: Clean up ???
comments and other comments. Add support for getter-specific
and setter-specific preconditions. Detect the error of putting
a field in the wrong subrange. Misc cleanup.
(Node_Field vs. Entity_Field): Clean up Nmake. Improve
comments.
* gen_il-utils.ads: Misc cleanup. Move...
* gen_il-internals.ads: ... here.
* gen_il-utils.adb: Misc cleanup. Move...
* gen_il-internals.adb: ... here.
* gen_il-fields.ads: Move Was_Default_Init_Box_Association,
which was in the wrong subrange. Add comments. Misc cleanup.
* gen_il-types.ads: Add Named_Access_Kind.
* sinfo-cn.adb: Clean up ??? comments and other comments.
Remove redundant assertions.
* einfo.ads, sinfo.ads: Clean up ??? comments and other
comments. Remove all the comments indicating field offsets.
These are obsolete now that Gen_IL computes the offsets
automatically.