gas: minor reformatting in command line help and doc

- help message: add a comma between the short and long option
- as doc:
  - brief summary of how to invoke gas: separate [-w] [-x] on a new line as those
  two options have nothing to do with the warning options.
  - reordering of the warning options to have the same order as the listing.
  - no-warn option description: change an "and" to a "or", as it is either the short
  or long option to use, but not both at the same time.
- remove trailing whitespaces.

gas/as.c

@@ -333,7 +333,7 @@ Options:\n\
   fprintf (stream, _("\
   -f                      skip whitespace and comment preprocessing\n"));
   fprintf (stream, _("\
-  -g --gen-debug          generate debugging information\n"));
+  -g, --gen-debug         generate debugging information\n"));
   fprintf (stream, _("\
   --gstabs                generate STABS debugging information\n"));
   fprintf (stream, _("\
@@ -361,9 +361,9 @@ Options:\n\
   fprintf (stream, _("\
   -K                      warn when differences altered for long displacements\n"));
   fprintf (stream, _("\
-  -L,--keep-locals        keep local symbols (e.g. starting with `L')\n"));
+  -L, --keep-locals       keep local symbols (e.g. starting with `L')\n"));
   fprintf (stream, _("\
-  -M,--mri                assemble in MRI compatibility mode\n"));
+  -M, --mri               assemble in MRI compatibility mode\n"));
   fprintf (stream, _("\
   --MD FILE               write dependency information in FILE (default none)\n"));
   fprintf (stream, _("\
@@ -388,7 +388,7 @@ Options:\n\
   fprintf (stream, _("\
   --version               print assembler version number and exit\n"));
   fprintf (stream, _("\
-  -W  --no-warn           suppress warnings\n"));
+  -W, --no-warn           suppress warnings\n"));
   fprintf (stream, _("\
   --warn                  don't suppress warnings\n"));
   fprintf (stream, _("\

gas/as.h

@@ -315,7 +315,7 @@ COMMON bool flag_macro_alternate;
 COMMON unsigned char flag_readonly_data_in_text; /* -R */
 
 /* True if warnings should be inhibited.  */
-COMMON int flag_no_warnings; /* -W */
+COMMON int flag_no_warnings; /* -W, --no-warn */
 
 /* True if warnings count as errors.  */
 COMMON int flag_fatal_warnings; /* --fatal-warnings */

gas/doc/as.texi

@@ -260,7 +260,8 @@ gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
  [@b{--size-check=[error|warning]}]
  [@b{--statistics}]
  [@b{-v}] [@b{-version}] [@b{--version}]
- [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}] [@b{-w}] [@b{-x}]
+ [@b{-W}] [@b{--no-warn}] [@b{--warn}] [@b{--fatal-warnings}]
+ [@b{-w}] [@b{-x}]
  [@b{-Z}] [@b{@@@var{FILE}}]
  [@var{target-options}]
  [@b{--}|@var{files} @dots{}]
@@ -983,12 +984,12 @@ Print the @command{as} version and exit.
 @itemx --no-warn
 Suppress warning messages.
 
-@item --fatal-warnings
-Treat warnings as errors.
-
 @item --warn
 Don't suppress warning messages or treat them as errors.
 
+@item --fatal-warnings
+Treat warnings as errors.
+
 @item -w
 Ignored.
 
@@ -2863,7 +2864,7 @@ option @samp{-v} (which you can also spell as @samp{-version}) on the
 command line.
 
 @node W
-@section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
+@section Control Warnings: @option{-W}, @option{--no-warn}, @option{--warn}, @option{--fatal-warnings}
 
 @command{@value{AS}} should never give a warning or error message when
 assembling compiler output.  But programs written by people often
@@ -2874,22 +2875,24 @@ made.  All such warnings are directed to the standard error file.
 @kindex --no-warn
 @cindex suppressing warnings
 @cindex warnings, suppressing
-If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
+If you use the @option{-W} or @option{--no-warn} option, no warnings are issued.
 This only affects the warning messages: it does not change any particular of
 how @command{@value{AS}} assembles your file.  Errors, which stop the assembly,
 are still reported.
 
+@kindex --warn
+@cindex outputing warnings
+@cindex warnings, switching on
+Warnings are switched on by default. They can be switched off with @option{-W} or
+@option{--no-warn}. Specifying the @option{--warn} again later on the command line
+will switch on warnings again, and cause them to be output as usual.
+
 @kindex --fatal-warnings
 @cindex errors, caused by warnings
 @cindex warnings, causing error
 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
 files that generate warnings to be in error.
 
-@kindex --warn
-@cindex warnings, switching on
-You can switch these options off again by specifying @option{--warn}, which
-causes warnings to be output as usual.
-
 @node Z
 @section Generate Object File in Spite of Errors: @option{-Z}
 @cindex object file, after errors