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
@@ -7804,7 +7807,7 @@ section, using the endian model of the target.  If an expression will not fit
 in two bytes, a warning message is displayed and the least significant two
 bytes of the expression's value are used.  If an expression cannot be evaluated
 at assembly time then relocations will be generated in order to compute the
-value at link time.  
+value at link time.
 
 This directive does not apply any alignment before or after inserting the
 values.  As a result of this, if relocations are generated, they may be