* snames.ads-tmpl: Add Name_Rational and pragma Rational.
* par-prag.adb: Recognize pragma Rational.
* opt.ads (Rational_Profile): flag to control compatibility mode
with Rational compiler.
* sem_ch8.adb (Analyze_Subprogram_Renaming): When Rational profile
is enable, accept renaming declarations where the new subprogram
and the renamed entity have the same name.
* sem_prag.adb (analyze_pragma): Add pragma Rational, and recognize
Rational as a profile.