[ARM][doc] Document deprecation of pre-ARMv4T architecture revisions

	* doc/invoke.texi (ARM Options): Add note on deprecation of pre-ARMv4T
	architecture revisions.

From-SVN: r235029

gcc/ChangeLog

+2016-04-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* doc/invoke.texi (ARM Options): Add note on deprecation of pre-ARMv4T
+	architecture revisions.
+
 2016-04-15  Bernd Schmidt  <bschmidt@redhat.com>
 
 	* config/i386/i386-protos.h (ix86_using_red_zone): Declare.

gcc/doc/invoke.texi

@@ -13974,6 +13974,8 @@ of the @option{-mcpu=} option.  Permissible names are: @samp{armv2},
 @samp{armv7ve}, @samp{armv8-a}, @samp{armv8-a+crc}, @samp{armv8.1-a},
 @samp{armv8.1-a+crc}, @samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
 
+Architecture revisions older than @option{armv4t} are deprecated.
+
 @option{-march=armv7ve} is the armv7-a architecture with virtualization
 extensions.