* bindgen.adb Comment reformatting. Update the list of run-time globals.
(Gen_Adainit_Ada): Add the declaration, import and value set for
configuration flag Canonical_Streams.
(Gen_Adainit_C): Add the declaration and initial value of external
symbol __gl_canonical_streams.
* init.c: Update the list of global values computed by the binder.
* opt.ads: Add flag Canonical_Streams.
* par-prag.adb (Prag): Include Pragma_Canonical_Streams to the list of
semantically handled pragmas.
* sem_prag.adb: Add an entry into enumeration type Sig_Flags.
(Analyze_Pragma): Add case for pragma Canonical_Streams.
* snames.adb: Add character value for name Canonical_Streams.
* snames.ads:
Add Name_Canonical_Streams to the list of configuration pragmas.
Add Pragma_Canonical_Streams to enumeration type Pragma_Id.
* snames.h: Add a definition for Pragma_Canonical_Streams.
* s-ststop.adb:
Add a flag and import to seize the value of external symbol
__gl_canonical_streams. Update comment and initial value of constant
Use_Block_IO.
* gnat_rm.texi: Add section of pragma Canonical_Streams.
* gnat_ugn.texi:
Add pragma Canonical_Streams to the list of configuration pragmas.
From-SVN: r138407
