[patch] Add -q in help info and doc

[Mingjie Xing <mingjie dot xing at gmail dot com>]

Hello,

I notice that "-q" and "--silent" options are not mentioned in gdb's
help information. This patch just adds them and updates the document.

Besides, most options in gdb document are using "-" prefix instead of "--".

ChangeLog

        * gdb.texinfo (Invoking GDB): Add -q and --quiet.
        * main.c (print_gdb_help): Add -q and --silent.

Is it OK?

Best regards,
Mingjie

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 9f7fa18..a0fb66d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -885,10 +885,11 @@ This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set
 @code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}.
 
 You can run @code{@value{GDBP}} without printing the front material, which describes
-@value{GDBN}'s non-warranty, by specifying @code{-silent}:
+@value{GDBN}'s non-warranty, by specifying @code{--silent}
+(or @code{-q}/@code{--quiet}):
 
 @smallexample
-@value{GDBP} -silent
+@value{GDBP} --silent
 @end smallexample
 
 @noindent
diff --git a/gdb/main.c b/gdb/main.c
index a9fc378..108759d 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -1173,7 +1173,8 @@ Output and user interface control:\n\n\
   fputs_unfiltered (_("\
   --dbx              DBX compatibility mode.\n\
   --xdb              XDB compatibility mode.\n\
-  --quiet            Do not print version number on startup.\n\n\
+  -q, --quiet, --silent\n\
+                     Do not print version number on startup.\n\n\
 "), stream);
   fputs_unfiltered (_("\
 Operating modes:\n\n\