[docs][llvm-extract] Add missing alias/bb options

[jsji]

Summary

llvm-extract get serveral new options, but we forgot to update doc.
This patch update the doc.

[volkan]

LGTM except the issue above. Thanks for updating the docs.

llvm/docs/CommandGuide/llvm-extract.rst

84

I think you meant -recursive here.

[jsji]

llvm/docs/CommandGuide/llvm-extract.rst

84

Good catch. Thanks!

llvm/docs/CommandGuide/llvm-extract.rst

 
 The :program:`llvm-extract` command reads its input from standard input if
 filename is omitted or if filename is ``-``.  The output is always written to
 standard output, unless the **-o** option is specified (see below).
 
 OPTIONS
 -------
 
+**--alias** *alias-name*
+
+ Extract the alias named *function-name* from the LLVM bitcode.  May be
+ specified multiple times to extract multiple alias at once.
+
+**--ralias** *alias-regular-expr*
+
+ Extract the alias matching *alias-regular-expr* from the LLVM bitcode.
+ All alias matching the regular expression will be extracted.  May be
+ specified multiple times.
+
+**--bb** *basic-block-specifier*
+
+ Extract basic blocks(s) specicified in *basic-block-specifier*. May be 
+ specified multiple times. Each <function:bb[;bb]> specifier pair will create 
+ a function. If multiple basic blocks are specified in one pair, the first 
+ block in the sequence should dominate the rest. 
+
+**--delete**
+
+ Delete specified Globals from Module.
+
 **-f**
 
  Enable binary output on terminals.  Normally, :program:`llvm-extract` will
  refuse to write raw bitcode output if the output stream is a terminal.  With
  this option, :program:`llvm-extract` will write raw bitcode regardless of the
  output device.
 
 **--func** *function-name*

  Extract the global variable(s) matching *global-regular-expr* from the LLVM
  bitcode.  All global variables matching the regular expression will be
  extracted.  May be specified multiple times.
 
 **--keep-const-init**
 
  Preserve the values of constant globals.
 
+**--delete**
+
+ Recursively extract all called functions
+
 **-help**
 
  Print a summary of command line options.
 
 **-o** *filename*
 
  Specify the output filename.  If filename is "-" (the default), then
  :program:`llvm-extract` sends its output to standard output.